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Article

Genetic Diversity of Leuconostoc mesenteroides Isolates from Traditional Montenegrin Brine Cheese

by
Werner Ruppitsch
1,*,
Andjela Nisic
2,
Patrick Hyden
3,
Adriana Cabal
1,
Jasmin Sucher
1,
Anna Stöger
1,
Franz Allerberger
1 and
Aleksandra Martinović
2,*
1
Institute of Medical Microbiology and Hygiene, Austrian Agency for Health and Food Safety, 1090 Vienna, Austria
2
Centre of Excellence for Digitalization of Microbial Food Safety Risk Assessment and Quality Parameters for Accurate Food Authenticity Certification (FoodHub), University of Donja Gorica, 81000 Podgorica, Montenegro
3
Department of Microbiology and Ecosystem Science, University of Vienna, 1090 Vienna, Austria
*
Authors to whom correspondence should be addressed.
Microorganisms 2021, 9(8), 1612; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9081612
Submission received: 18 June 2021 / Revised: 26 July 2021 / Accepted: 27 July 2021 / Published: 28 July 2021
(This article belongs to the Special Issue Functional Characterization of Lactic Acid Bacteria)
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Abstract

:
In many dairy products, Leuconostoc spp. is a natural part of non-starter lactic acid bacteria (NSLAB) accounting for flavor development. However, data on the genomic diversity of Leuconostoc spp. isolates obtained from cheese are still scarce. The focus of this study was the genomic characterization of Leuconostoc spp. obtained from different traditional Montenegrin brine cheeses with the aim to explore their diversity and provide genetic information as a basis for the selection of strains for future cheese production. In 2019, sixteen Leuconostoc spp. isolates were obtained from white brine cheeses from nine different producers located in three municipalities in the northern region of Montenegro. All isolates were identified as Ln. mesenteroides. Classical multilocus sequence tying (MLST) and core genome (cg) MLST revealed a high diversity of the Montenegrin Ln. mesenteroides cheese isolates. All isolates carried genes of the bacteriocin biosynthetic gene clusters, eight out of 16 strains carried the citCDEFG operon, 14 carried butA, and all 16 isolates carried alsS and ilv, genes involved in forming important aromas and flavor compounds. Safety evaluation indicated that isolates carried no pathogenic factors and no virulence factors. In conclusion, Ln. mesenteroides isolates from Montenegrin traditional cheeses displayed a high genetic diversity and were unrelated to strains deposited in GenBank.

1. Introduction

The genus Leuconostoc (Ln.) currently comprises 14 species and eight subspecies, all being Gram-positive, non-spore-forming, non-motile Lactic Acid Bacteria (LAB). Within the genus Leuconostoc, Ln. mesenteroides, Ln. pseudomesenteroides and Ln. lactis have their role in food fermentation and can be isolated from various food-related ecological niches, including beverages, meat and dairy products, and some plant materials, implying wide distribution and specialized adaptation to these diverse environments [1,2,3,4]. The first description of Ln. mesenteroides was by Van Tieghem in 1878 and was later proposed as the type strain [5]. In 1983, Ln. dextranicum and Ln. cremoris were reclassified as subspecies of Ln. mesenteroides due to the common properties they shared [6] and their high degree of relatedness shown by DNA—DNA hybridization [5].
In the food production, Leuconostoc spp. are usually applied as an adjunct culture in combination with the fast acid producing Lactococcus spp., as undefined mixed (DL) type starter cultures, contributing to aroma and texture formation of the final products through citrate degradation and production of diacetyl, acetoin, and carbon dioxide [7,8]. Due to its aroma producing traits, Ln. mesenteroides has become known as “the aroma bacterium” [9]. Leuconostoc spp. are characterized by heterolactic fermentation [10] through the phosphoketolase pathway (PKP), resulting in the formation of aroma and flavor compounds such as lactic acid, acetic acid, ethanol, and CO2 (responsible for “eye formation” in some cheeses) [8]. Genetic elements involved in the production of aroma and flavor compounds include the acetoin reductase gene butA, the citrate inducible cit operon, and genes involved in the biosynthesis of branched aminoacids like the acetolactate synthase gene alsS and genes of the isoleucine-leucin (ilv) synthesis operon. These compounds contribute to the flavor of the products, while biosynthesis of bacteriocins [11,12,13] has preservation potential by inhibiting the growth of pathogenic bacteria like Listeria spp., Escherichia coli, Staphylococcus aureus, or Salmonella enterica serovars Typhimurium and Typhi [11,12,13], positively affecting the quality and safety of the final product [14].
Many traditional dairy products are manufactured without starter cultures [15] and are recognized as an essential part of a country’s identity, culture, and heritage [16,17]. In these traditional dairy products, naturally occurring Leuconostoc spp., together with mesophilic lactobacilli known as non-starter LAB (NSLAB), play an important role in flavor development, accounting for the characteristics and the quality of traditional food products [15]. In addition, Leuconostoc spp. strains obtained from traditional cheese products can be valuable for future dairy food production [17], by improving the product quality [18], since their properties ultimately affect the characteristics and quality of the final products. Therefore, the isolation and accurate characterization of Leuconostoc spp. strains, as well as other NSLAB species, can provide necessary information for their selection and application with the aim of preservation and improvement of quality and safety of traditional food products [17]. With the evolution of sequencing technologies from Sanger sequencing to whole genome sequencing (WGS), the genome-based characterization of Leuconostoc spp. may present an innovative tool to ensure consistent manufacturing of high quality and safe traditional food products [19,20]. Despite the proven influence of Leuconostoc spp. to the final characteristics of cheeses, information on the genomic diversity of Leuconostoc spp. obtained from cheese is still scarce [20,21,22]. Up to now, three different multilocus sequence typing [MLST] schemes have been published to investigate strain diversity of approximately 200 isolates from environmental and dairy sources [23,24,25]. Among all those 200 isolates, only seven cheese isolates were analyzed by MLST [23,24,25]. Unfortunately, publicly available databases do not exist for any of the three published MLST schemes [23,24,25], making a direct strain comparison impossible. In addition, in today’s genomic era, only seven Ln. mesenteroides genomes (DSM20484, FM06, LbT16, LbE15, LbE16, LN25 and T26) derived from cheese are available in GenBank (accessed 15 June 2021) [20,21,22,26,27]. However, genome sequencing remains the most powerful tool for characterization of bacterial strains. Prospective comparison and coupling of genome data and other “omics” data [19,28] with phenotypic data and the use of genome-scale metabolic models [GSMMs] may facilitate the prediction of metabolic patterns and easier comparison of metabolic capacities of organisms [8]. The combination of all these modern technologies may assist the rapid and efficient genetic marker-based selection of the most suitable strains even though predictive microbiology is currently still a complex and challenging process [8,19,29].
The aim of this study was to explore the genetic diversity of Ln. mesenteroides isolates obtained from Montenegrin brine cheeses using whole genome sequencing to prove the origin of the Montenegrin strains that can be used in future industrial cheese production. This could lead to more controlled cheese production featuring improved product safety with the preserved indigenous sensory characteristics as an added value. The use of these genome data could represent a useful tool for authentication of traditional dairy products.

2. Materials and Methods

2.1. Origin and Cultivation of Isolates

Bacteria were isolated from 13 different white brine ripened traditional cheeses collected during spring and summer 2019 from nine producers from the three municipalities Pljevlja, Šavnik, and Žabljak in the northern region of Montenegro (Supplementary Figure S1 Regions of Montengro), as described previously [30]. Briefly, for each sample, 20 g of cheese was added to 180 mL sterile 2% (w/v) sodiumcitrate solution and homogenized for 2 min in an Omni mixer (Omni International, Waterbury, CT, USA). For enumeration, serial dilutions in Ringer’s solution were plated on de Man, Rogosa, Sharpe (MRS), and M17 agar plates (HiMedia, Mumbai, India) and incubated at 30 °C for 72 h. Isolates were biochemically characterized for their acidification and post-acidification ability, growth at different temperatures and NaCl concentrations, and their ability for lactose degradation. Isolates were stored in MRS and M17 medium supplemented with 15% glycerol (v/v) at −80 °C, and, for revitalization, subcultured three times in the respective broths (MRS and M17) at 30 °C overnight.
Up to ten single colonies were selected from MRS and/or M17 agar plates and subcultured for further processing. Species confirmation was carried out using matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) [31] on a MALDI-TOF Microflex LT/SH with database MBT Compass IVD 4.2 according to the manufacturer’s instructions (Bruker, Billerica, MA, USA).

2.2. Biochemical Testing

2.2.1. Growth at Different Temperatures

Overnight cultures grown at 30 °C were inoculated in MRS broth and incubated for 24 h at 4, 10, 15, 30 (optimal growth temperature, used as control), and 45 °C. The optical density was measured on a Jasco UV/VIS spectrophotometer V-730 (Jasco, Cremella, Italy) at 560 nm (OD560).

2.2.2. Production of CO2

The production of CO2 from glucose was determined as described previously [32]. Briefly, bacterial cultures (50 µL) were added into a test tube containing 10 mL of suitable broth supplemented with 1% of glucose (Tokyo Chemical Industry, Tokyo, Japan) and a Durham’s tube. After 24–48 h of incubation at 30 °C, gas production was assessed: if the gas accumulated in the Durham’s tube to more than one third of its capacity, the result was considered positive.

2.2.3. Salt Tolerance

The evaluation of salt tolerance was performed as described previously [32,33]. Briefly, salt content of tubes containing 3 mL of MRS broth was adjusted to a final concentration of 2%, 3%, 4.5%, or 6.5% (w/v) NaCl. Tubes were inoculated with overnight cultures of the strains and incubated at 30 °C for 24 h. Bacteria grown in MRS broth without NaCl were used as controls. The optical density was measured on a Jasco UV/VIS spectrophotometer V-730 at 560 nm (OD560).

2.2.4. Acidification and Post-Acidification Ability in Milk

Acidification and post acidification ability was tested as described previously by inoculating 50 mL ultra-high temperature (UHT) processed skimmed cow’s milk (Imlek, Belgrade, Serbia) [34] with 50 µL of broth culture and incubated at 30 °C for 48 h. The resulting pH values, measured after 2, 4, 6, 8, 12, and 24 h post-acidification, were investigated by measuring the pH of the inoculated skimmed milk after 48 h of incubation [34]. pH of milk was measured with a WTW pH Meter inoLab ph 7110 (Xylem Analytics, Weilheim, Germany).

2.2.5. Catalase Testing

Bacterial cells from a solid nutrient medium were transferred to empty Petri dishes. In addition, 1–2 drops of 3% hydrogen peroxide were dropped on the cells. Formation of air bubbles (production of oxygen due to the presence of catalase) was examined visually.

2.2.6. Ability for Formation of Exopolysaccharides (EPS)

EPS formation ability was performed by identifying mucous-producing colonies grown on MRS agar plates. Additionally, mucoid colonies were stretched with an inoculation loop to detect the production of long filaments. If the mucus producing colonies or the formation of long filaments was missing, the strain was considered EPS negative.

2.3. Antimicrobial Susceptibility Testing

The Kirby–Bauer disk diffusion test was used to determine antimicrobial susceptibility of strain INF36 against erythromycin (15 µg, Bioanalyse, Ankara, Turkey) and of strain INF117 against ampicillin (10 µg) and penicillin (1U) (Bioanalyse, Ankara, Turkey). The disk diffusion patterns were evaluated according to the microbiological breakpoints for selected lactic acid bacteria as defined by EFSA [35,36].

2.4. DNA Extraction and Whole Genome Sequencing

For whole genome sequencing, high quality genomic DNA was isolated from overnight cultures grown in M17 or MRS using the MagAttract HMW DNA Kit (Qiagen, Hilden, Germany) according to the protocol for Gram-positive bacteria following the manufacturer’s instructions (Qiagen). The amount of input DNA was quantified on a Lunatic instrument (Unchained Labs, Pleasanton, CA, USA). Ready to sequence libraries were prepared using the Nextera XT DNA library preparation kit (Illumina, San Diego, CA, USA) according to the instructions of the manufacturer. Paired-end sequencing with a read length of 2 × 300 bp using Reagent Kit v3 chemistry (Illumina, San Diego, CA, USA) was performed on a Miseq instrument (Illumina, San Diego, CA, USA) according to the instructions of the manufacturer (Illumina).

2.5. Sequence Data Analysis

All study isolates were sequenced to obtain a coverage of at least 20-fold. Raw reads were quality controlled using FastQC v0.11.9 and de novo assembled using SPAdes (version 3.11.1) [37] to produce draft genomes. Contigs were filtered for a minimum coverage of 5× and a minimum length of 200 bp using SeqSphere+ software v7.2.3 (Ridom, Münster, Germany). Confirmation of species identification was done by 16S rRNA analysis [38], https://tygs.dsmz.de (accessed on 27 November 2020), Mash distance v2.3 [39], and ribosomal multilocus sequence typing (rMLST) [40]. Average nucleotide identity (ANI) was determined using FastANI v1.32 [41] in all-versus-all fashion using default parameters. A Type Strain Genome Server analysis (TYGS) tool from the German Collection of Microorganisms and Cell Cultures GmbH (DSMZ) was used for digital DNA-DNA hybridization (dDDH) using formula d4 as recommended for draft genomes (https://tygs.dsmz.de (accessed on 27 November 2020)) to assign the isolates to Ln. mesenteroides subspecies [40], https://tygs.dsmz.de (accessed on 27 November 2020).
Subtyping of all 16 Ln. mesenteroides isolates was conducted in SeqSphere+ v7.2.3 using a recently published eight-gene multilocus sequence typing (MLST) scheme comprising the eight loci carB, groeL, murC, pheS, pyrG, recA, rpoB, and uvrC [25] and a newly defined ad hoc core genome multilocus sequence typing (cgMLST) scheme. For definition of the cgMLST scheme, a genome-wide gene-by-gene comparison was performed using the complete genome of strain Ln. mesenteroides subsp. mesenteroides ATCC 8293 as a reference genome and 18 complete genomes of Ln. mesenteroides available in GenBank as query genomes (Supplementary Table S1 cgMLST_scheme_data). The resulting ad hoc cgMLST scheme comprised 960 core genome target genes and 935 accessory genome target genes. Sixty genes of the ATCC 8293 genome were discarded since they did not fulfil the default quality criteria (Supplementary Table S1 cgMLST_scheme_data). Seven of the eight MLST targets [25] were also part of our cgMLST scheme while one target (uvrC) belonged to the accessory genome. For phylogenetic analysis, a minimum spanning tree (MST) was calculated based on the defined 960-target cgMLST scheme. Based on the 17 allelic differences observed between the query strains NBRC107766 and ATCC19254 (both are the same strain but originating from different repositories and sequenced at different laboratories), an arbitrary complex type threshold of 45 allelic differences was applied for detection of related isolates.
BAGEL4 [42] was used to screen for bacteriocins, and antiSMASH5 [43] was used to screen for secondary metabolite “biosynthetic gene clusters”. To address biosafety concerns towards starter culture microorganisms, all 16 isolates were analyzed for the presence of pathogenic factors [44], plasmids [45], and virulence genes [46] using PathogenFinder 1.1, PlasmidFinder 2.1, and VirulenceFinder 2.0 available from the Center for Genomic Epidemiology [http://www.genomicepidemiology.org/ (accessed on 3 December 2020)]. Antibiotic resistance genes were detected using the ResFinder 4.1 tool with default settings (>90% identity and >60% coverage) [47] and the Comprehensive Antibiotic Resistance Database (CARD) applying perfect and strict hits search criteria [48].

2.6. Gene Presence and Absence

Detailed analysis of additional genomic information was performed for all 16 genomes and 12 reference strains: KMB608, ATCC8293, 406, 213M0, WC0331, DRC1506, ATCC19254, LN08, DSM20484, LN32, NBRC100495, and LbE15. The contigs of each assembly were filtered for a minimum length of 1000 nucleotides. Genes were predicted using prodigal v2.6.3 [49] with default parameters, and orthologous groups were calculated with OrthoFinder v1.4.2 [50]. Orthologous groups with differences in presence/absence were selected for visualization. Additionally, a species tree was created from the orthologous groups using default parameters for Orthofinder. Annotation of predicted genes was performed using NCBI BLAST+ v2.10.0 [51].

2.7. Nucleotide Sequence Accession Numbers

This Leuconostoc mesenteroides whole genome shotgun (WGS) project has been deposited in DDBJ/ENA/GenBank under the BioProject No. PRJNA706746. This Whole Genome Shotgun project has been deposited at DDBJ/ENA/GenBank under the accession JAGFYI000000000—JAGFYL000000000, JAFREA000000000—JAFREC000000000, and JAFRDS000000000—JAFRDZ000000000. The version described in this paper is version JAGFYI010000000—JAGFYL010000000, JAFREA010000000—JAFREC010000000, and JAFRDS010000000—JAFRDZ010000000.

3. Results

3.1. Biochemical Properties

Sixteen Ln. mesenteroides isolates were successfully isolated and identified by MALDI-TOF-MS from 13 Montenegrin brine cheeses (Supplementary Figure S1 Regions of Montenegro, Table 1). All isolates were Gram-positive, catalase negative, and had no ability for formation of exopolysaccharides (EPS). The mean number of viable bacterial cells was in the range between 41 to 92 cfu/g cheese. The acidification ability of the tested strains was in the range of pH 4.3–5.9 (24 h), while post acidification ability was between pH 4.2–5.7 (48 h). After 48 h of incubation at 30 °C, the pH in broths supplemented with 1% lactose was in the range of 4.4 to 5.5. Six tested isolates exhibited an ability to grow at 6.5% NaCl concentration, 11 strains at 4.5%, while three strains did not grow at 2% NaCl concentration. Both isolates obtained from producer A (INF2 and INF3b) showed growth ability at a salt concentration of 2%, but did not grow at higher salt concentrations. Isolate INF82b (producer D) was only growing at a salt concentration of 4.5%. Ten isolates showed an ability to grow at 45 °C, three isolates INF3b (producer A), INF36 (producer B), and INF46 (producer C) had the ability to grow at 4 °C (Table 1).

3.2. Species and Subspecies Identification

Mash distance analysis, 16s rRNA gene sequence analysis (Supplementary Figure S2 16S rRNA), and ribosomal multilocus sequence typing (rMLST) (https://pubmlst.org/rmlst (accessed on 20 November 2020)) and ANI analysis (>97% identity; cut-off >95% identity) (Supplementary Table S2 ANI, Supplementary Figure S3 ANI) confirmed the MALDI-TOF-MS identification of all 16 isolates as Ln. mesenteroides. Type Strain Genome Server analysis (TYGS) assigned 10 isolates to the subspecies Ln. mesenteroides mesenteroides and two each of the isolates to subspecies Ln. mesenteroides dextranicum, Ln. mesenteroides cremoris, and Ln. mesenteroides jonggajibkimichii (Figure 1). Digital DNA-DNA Hybridization (dDDH) using formula d4 (https://tygs.dsmz.de (accessed on 20 November 2020)) revealed a similarity of ≥92.5% of the ten Ln. mesenteroides mesenteroides to Ln. mesenteroides mesenteroides ATCC 8293 (Supplementary Table S3 dDDH). Two isolates showed a dDDH similarity to subspecies Ln. mesenteroides dextranicum DSM 20484 of ≥97.8%, while four isolates were not clearly assignable to a subspecies by dDDH: INF2 and INF98 had dDDH values of 90.5% to Ln. mesenteroides cremoris and ≥93% to Ln. mesenteroides dextranicum, and INF117 and INF166 had dDDH values of ≥91.5% to Ln. mesenteroides jonggajibkimichii, ≥92.4% to Ln. mesenteroides dextranicum, and ≥92.6% to Ln. mesenteroides mesenteroides (Supplementary Table S3 dDDH). ANI analysis (>97% identity, cut-off >95% identity) (Supplementary Table S2 ANI, Supplementary Figure S3 ANI) and core genome analysis confirmed the dDDH results; cgMLST positioned these isolates on branches comprising strains of different subspecies (Figure 2). The Montenegrin cheese Ln. mesenteroides isolates had a genome size between 2.0 Mb and 2.3 Mb, had 2074 to 2368 genes, 1905 to 2221 coding genes, 85 to 151 pseudo genes, and 57 to 65 RNA genes (Supplementary Table S4 genome data).

3.3. Whole Genome Sequence Based Subtyping

MLST and cgMLST based characterization of all 16 Ln. mesenteroides isolates and 72 Ln. mesenteroides genomes available in GenBank (72 genomes fulfilled the quality criteria of at least ≥90% good core genome targets) revealed a high diversity of the Montenegrin Ln. mesenteroides isolates (Figure 2, Supplementary Figure S4 MLST). MLST and cgMLST showed comparable results but with the advantage of a higher resolution for the core genome approach.
Briefly, the 16 Montenegrin brine cheese isolates were assigned to twelve different MLST profiles differing between zero and eight alleles. Identical MLST profiles were found for INF2 and INF98 from producers A and D (MLST complex 1); INF82b and INF94 both from producer D (MLST complex 2); INF46 and INF157 from producers C and H (MLST complex 3); INF36, INF90 and 213MO from producers B and D and GenBank, respectively (MLST complex 4); and INF103 from producer E and M11, 406, and AtHG50 from GenBank (MLST complex 5) (Supplementary Figure S4 MLST). CgMLST differentiated the Montenegrin isolates by one to 860 alleles from each other (Figure 2). CgMLST confirmed the MLST based clustering of complex 1 to complex 3 when applying a core genome cluster type threshold of 45 alleles (Figure 2, Supplementary Table S4 genome data). MLST complex 1 isolates INF2 and INF98, MLST complex 2 isolates INF82b and INF94, and MLST complex 3 isolates INF46 and INF157 differed by 41, five, and one allele(s) in their core genome, respectively (Figure 2). CgMLST revealed with an allelic distance of 41 a closer relatedness of isolate INF90 to the MLST complex 2 isolates INF94 and INF82b than to the MLST complex 4 isolates INF36 and 213MO with an allelic distance of >170 alleles (Figure 2). For MLST complex 5 cgMLST analysis differentiated isolate INF103 from 138 to 163 alleles from the GenBank isolates 406, M11, and AtHG50. Isolates INF2 and INF3 obtained from two cheeses of the same type from producer A differed by 839 alleles in their core genome (Figure 2). Six isolates INF82a, INF82b, INF90, INF92, INF94, and INF98 obtained from three cheeses of the same type from producer D differed by five to a maximum of 860 alleles in their core genome (Table 1, Figure 2). Isolates INF82a and INF82b obtained from the same cheese from producer D differed by 860 alleles (Figure 2). The cgMLST based comparison of the Montenegrin Ln. mesenteroides isolates with isolates available from GenBank revealed an allelic difference from 138 to a maximum of 646 alleles (Figure 2). The closest related strains available from GenBank were Ln. mesenteroides strain 406 and 213MO, two strains isolated from Mongolian mare milk differing by 138 alleles, respectively, and 165 alleles from strain INF103 from producer E (Figure 2). CgMLST revealed 295 to 865 allelic differences between the Montenegrin isolates and the Ln. mesenteroides subspecies reference strains (Supplementary Table S4 genome data). CgMLST results were concordant with TYGS and ANI analysis (Supplementary Table S2 ANI, Supplementary Figure S3 ANI, Supplementary Table S4 genome data, Figure 1).

3.4. Detection of Bacteriocin and Secondary Metabolite Genes

All isolates but one carried genes of the bacteriocin biosynthetic gene clusters, ten out of 16 carried a betalactone biosynthesis gene, and all carried a type III polyketide synthase gene (T3PKS) (Table 2). Eight out of our 16 Leuconostoc strains carried genes necessary for citrate metabolism (citCDEFG operon) (Figure 3), 14 isolates had the acetoin reductase gene butA and all isolates carried genes necessary for the biosynthesis of branched aminoacids acetolactate synthase alsS and isoleucine synthesis operon ilv.

3.5. Safety Evaluation

Safety evaluation indicated that none of the 16 isolates carried pathogenic and virulence factors. Five isolates carried plasmids. The CARD database identified a C656T transition in the 23S rRNA gene of isolate INF36, conferring resistance to erythromycin and clindamycin (100% identity, 10% coverage) using the CARD database. ResFinder did not detect this mutation in the 23S rRNA gene of isolate INF36. Disk diffusion testing revealed susceptibility of strain INF36 against erythromycin (Table 3). Isolate INF117 carried a partial blaTEM with 99.04% identity and 60.51% coverage to blaTEM-141 (and others) using ResFinder. CARD analysis (using the loose hits criteria) confirmed the presence of a partial blaTEM in isolate INF117 (97.5% identity and 55.94% coverage to several blaTEM) (Table 3). A BLAST search of the contig containing the partial blaTEM was performed, resulting in 100% coverage and 99.65% identity match to Ln. mesenteroides ATCC8293. Disk diffusion testing revealed susceptibility of strain INF117 against ampicillin and penicillin (Table 3).

3.6. Orthofinder Analysis

Orthofinder analysis assigned 57,889,803 genes (97.9% of total) to 3080 orthologous groups. The number of orthologous groups identified for our isolates ranged from 1873 to 2111 (mean: 1979). There were 1280 orthogroups present in all Leuconostoc subspecies and 1091 of these orthologous groups consisted entirely of single-copy genes (Figure 3).

4. Discussion

Traditional food products are an acknowledged part of the identity, culture, and heritage of a country and, in addition, they may serve as a valuable resource for future food production [16,17,52]. To explore the diversity of Leuconostoc spp. Isolates, we characterized in this study 16 Leuconostoc mesenteroides (Ln. mesenteroides) isolates obtained from 13 traditional Montenegrin brine cheeses from nine different producers by whole genome sequencing (WGS). To the best of our knowledge, our study comprises the largest set of Ln. mesenteroides strains from traditional cheese characterized biochemically and by WGS.
The biochemical abilities of strains were in the range of expected technological significance. Growth at low/high salt and or low/high temperatures of single isolates could not be linked to genotypes.
Nevertheless, genome sequencing is considered as a suitable tool for the selection of particularly suitable strains used as adjunct cultures for the production of traditional cheese [15,21,22,26]. Leuconostoc species were “Generally Regarded As Safe” (GRAS) organisms by the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) for food production [53,54]. Reports about clinical infections caused by Ln. mesenteroides [55] in combination with the role of LAB as a reservoir for antimicrobial resistances have changed the uncritical classification of LAB as GRAS. Antimicrobial resistance and multi-resistance have been described for several Ln. mesenteroides isolates [36,56]. Safety evaluation of the Montenegrin brine cheese isolates revealed that they carried no pathogenic factors and no virulence genes. However, two isolates carried antimicrobial resistance determinants. One isolate carried a fragment of the blaTEM, which also exists in the genomes of several other Ln. mesenteroides strains including reference strains ATCC 8293. For the second strain, we found for the first time in a Leuconostoc spp. isolate a C656T point mutation in the 23S rRNA gene. This mutation was detected for the first time in Clostridioides difficile (Clostridium difficile) conferring high resistance to erythromycin and low resistance to clindamycin [57]. However, this point mutation was not found via ResFinder analysis. Phenotypic testing revealed that both strains were susceptible against the respective antibiotics, which can be explained by the fact that the detected antimicrobial resistance gene fragments are non-functional.
Analysis of genes essential for the biosynthesis of secondary metabolites revealed that all but one strain carried genes of the bacteriocin biosynthetic gene clusters, which is an important natural feature in cheese production through inhibiting the growth of several important pathogenic bacteria. All strains carried a type III polyketide synthase gene essential for the biosynthesis of important secondary metabolites [43] and all isolates carried genes essential for the biosynthesis of branched aminoacids that contribute to flavor. Interestingly, only 50% of our Montenegrin cheese isolates carried the cítrate operon, which is essential for citrate metabolism and a characteristic of dairy Ln. mesenteroides strains [20].
To investigate strain diversity, a previously published MLST scheme [25] and our novel ad hoc core cgMLST scheme were used. Our ad hoc cgMLST scheme comprised 960 core targets in comparison to a recently published cgMLST scheme, which comprised 999 core genes [19]. We used a so-called “hard core genome” definition and 19 instead of 17 complete genomes for core genome generation, which resulted in the observed lower number of 960 core genome targets. All tested isolates except four had more than 97% good core genome targets. Type Strain Server Analysis (TYGS) [38] identified most of our isolated strains as subspecies Ln. mesenteroides mesenteroides, confirming recent findings that subspecies Ln. mesenteroides mesenteroides is better adapted to cheese production than other subspecies and also than subspecies Ln. mesenteroides cremoris, which is mainly used in commercial starter cultures [3]. In addition to subspecies Ln. mesenteroides mesenteroides, TYGS analysis assigned the remaining six Montenegrin brine cheese isolates to subspecies Ln. mesenteroides cremoris, Ln. mesenteroides jonggajibkimchii, and Ln. mesenteroides dextranicum. Isolates identified as Ln. mesenteroides mesenteroides and Ln. mesenteroides dextranicum by TYGS clustered appropriately with the respective subspecies available from GenBank when using dDDH, ANI, or our cgMLST approach. Four isolates were not accurately assignable by TYGS, ANI, or cgMLST to a Leuconostoc mesenteroides subspecies. All these methods placed them between different Leuconostoc subspecies. Congruent with TYGS and ANI, cgMLST analysis placed two of the Montenegrin isolates between strains previously identified as Ln. mesenteroides mesenteroides [20] and Ln. mesenteroides cremoris [26]. Two other Montenegrin isolates were placed between Ln. mesenteroides dextranicum strains isolated from Italian cheese [26] and Ln. mesenteroides mesenteroides strains isolated from sheep milk in Slovakia [unpublished, https://0-www-ncbi-nlm-nih-gov.brum.beds.ac.uk/biosample/SAMN09398940] (accessed on 25 February 2020). From this Italian study [26], diverse Ln. mesenteroides subspecies were recently reassigned to Ln. mesenteroides lineage M4 and Ln. mesenteroides lineage M1 [20], which confirmed our core genome results, i.e., clustering of these strains on the same branches. In contrast, all other Ln. mesenteroides cremoris strains available from GenBank clustered together and were unrelated to the Italian and our isolates. This awkward subspecies assignment indicates that Ln. mesenteroides lineage M1 and M4 strains have some specific features from diverse subspecies [20]. The four Montenegrin isolates that were not assignable to a subspecies (and related to lineage M1 and M4 isolates according to Frantzen et al., 2017) [20] had, in comparison to the other Montenegrin cheese isolates, a lower percentage of good core genome targets (≤97%). This lower number of core genes is also characteristic for Ln. mesenteroides cremoris ATCC19254 and Ln. mesenteroides jonggajibkimchii DRC1506 due to the loss of genes of these two Leuconostoc subspecies as a consequence of adaptation to their ecological niches [19,20]. Our results support recent findings that a taxonomic revision of the genus Leuconostoc should be considered and that some of the isolates available in GenBank have been assigned to the wrong subspecies due to the use of phenotypic properties [20,58].
MLST and cgMLST analysis revealed that the 16 Montenegrin Ln. mesenteroides cheese isolates showed a high diversity, which contrasts with isolates obtained from commercial starter cultures, which show a low genetic diversity [20,25]. This high diversity underlines the importance of traditional food products as a valuable source for strains with unique and interesting features to be used in the dairy industry as novel starter cultures or for production of functional dairy foods [15,18,52]. The observed high diversity of our Montenegrin Ln. mesenteroides isolates and, in addition, their non-relatedness to genomes of strains available from GenBank reflects that no commercial starter cultures were used to produce the traditional Montenegrin brine cheeses included in this study. Although we investigated only a small number of isolates, the observed diversity corresponds with results from previous studies showing a high strain diversity of Ln. mesenteroides obtained from a variety of food sources [23,24,25]. Isolation of different strains from the same cheese product of the same producer and the diversity of strains obtained from the same cheeses also indicate a variable composition of the Leuconostoc population in traditional cheeses, which may also affect the sensory characteristics and quality of the final products. However, more extensive studies are necessary to prove these findings. The differences between isolates from the same producer as well as from the neighboring regions might be explained by the specific natural plant biodiversity, which is strongly supported by the fact that, in Montenegro, the feeding of animals is still to the highest extent based on natural grazing, with a relatively low percentage of concentrate feeding [52]. Thus, genome-based characterization of Leuconostoc spp. may present an innovative tool to prove the origin of strains and to ensure consistent manufacture of high quality and safe traditional food products [19,20]. In the future, with the ongoing progress in multi-omics technologies, the prediction of gene functions, metabolic pathways, and inter-microbe interactions—particularly within starter cultures—may allow a selection of strains based on specific marker genes more efficiently [28]. Currently, the accurate prediction of metabolic patterns and the comparison of metabolic capacities of organisms using genome-scale metabolic models is still a major challenge or even impossible due to the lack of complete genomes [8].
In conclusion, Ln. mesenteroides isolates from the Montenegrin traditional brine cheeses show a high genetic diversity, which can be explained by the high level of plant biodiversity in Montenegro and the fact that the feeding of animals is mainly based on natural grazing. WGS based strain-typing proves the Montenegrin origin and endogenous status of strains. With the ongoing progress in predictive microbiology, indigenous cheese isolates with specific properties will become selectable and become available for standardization of the production, to preserve designation of origin as well as to create added-value sensory characteristics.

Supplementary Materials

The following are available online at https://0-www-mdpi-com.brum.beds.ac.uk/article/10.3390/microorganisms9081612/s1. Table S1. cgMLST_scheme_data; Table S2. ANI; Table S3. Dddh; Table S4. Genome data; Figure S1. Regions of Montenegro; Figure S2. 16S rDNA; Figure S3. ANI heatmap; Figure S4. MLST.

Author Contributions

Conceptualization, W.R. and A.M.; Data curation, W.R. and A.M.; Formal analysis, W.R., A.N. and A.M.; Funding acquisition, A.M.; Investigation, A.N., J.S. and A.S.; Methodology, W.R., A.N., P.H., A.C., J.S., A.S. and A.M.; Project administration, A.M.; Resources, W.R., F.A. and A.M.; Software, W.R., A.N., P.H., A.C. and J.S.; Supervision, W.R., F.A. and A.M.; Validation, W.R., A.M.; Visualization, W.R., A.N., P.H. and A.C.; Writing—original draft, W.R., F.A. and A.M.; Writing—review and editing, W.R., A.N., P.H., A.C., J.S., A.S., F.A. and A.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research project was funded through the grant of the Ministry of Science of Montenegro: Innovative project “Products and Process Innovation in the Montenegrin Food Industry, INNOFOOD”—Agriculture and food No. 01-2311/3.

Data Availability Statement

This Leuconostoc mesenteroides whole genome shotgun (WGS) project has been deposited in DDBJ/ENA/GenBank under the BioProject No. PRJNA706746. This Whole Genome Shotgun project has been deposited at DDBJ/ENA/GenBank under the accession JAGFYI000000000—JAGFYL000000000, JAGSYL000000000, JAFREA000000000—JAFREC000000000, JAFRDS000000000—JAFRDZ000000000. The version described in this paper is version JAGFYI010000000—JAGFYL010000000, JAGSYL010000000, JAFREA010000000—JAFREC010000000, JAFRDS010000000—JAFRDZ010000000.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Cogan, T.M.; Jordan, K.N. Metabolism of Leuconostoc bacteria. J. Dairy Sci. 1994, 77, 2704–2717. [Google Scholar] [CrossRef]
  2. Thunell, R.K. Taxonomy of the Leuconostocs. J. Dairy Sci. 1995, 78, 2514–2522. [Google Scholar] [CrossRef]
  3. Hemme, D.; Foucaud-Scheunemann, C. Leuconostoc, characteristics, use in dairy technology and prospects in functional foods. Int. Dairy J. 2004, 14, 467–494. [Google Scholar] [CrossRef]
  4. Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; Karamychev, V.; Polouchine, N.; et al. Comparative genomics of the lactic acid bacteria. Proc. Nat. Acad. Sci. USA 2006, 103, 15611–15616. [Google Scholar] [CrossRef] [Green Version]
  5. Garvie, E.I. Proposal of neotype strains for Leuconostoc mesenteroides (Tsenkovskii) van Tieghem, Leuconostoc dextranicum (Beijerinck) Hucker and Pederson, and Leuconostoc cremoris (Knudsen and Sørensen) Garvie. Int. J. Syst. Evol. Microbiol. 1979, 29, 149–151. [Google Scholar]
  6. Garvie, E.I. NOTES: Leuconostoc mesenteroides subsp. cremoris (Knudsen and Sørensen) comb. nov. and Leuconostoc mesenteroides subsp. dextranicum (Beijerinck) comb. nov. Int. J. Syst. Evol. Microbiol. 1983, 33, 118–119. [Google Scholar] [CrossRef]
  7. Van Mastrigt, O.; Abee, T.; Smid, E.J. Complete Genome Sequences of Lactococcus lactis subsp. lactis bv. diacetylactis FM03 and Leuconostoc mesenteroides FM06 Isolated from Cheese. Genome Announc. 2017, 5, e00633-e17. [Google Scholar]
  8. Özcan, E.; Selvi, S.S.; Nikerel, E.; Teusink, B.; Öner, E.T.; Çakır, T. A genome-scale metabolic network of the aroma bacterium Leuconostoc mesenteroides subsp. cremoris. Appl. Microbiol. Biotech. 2019, 103, 3153–3165. [Google Scholar] [CrossRef] [PubMed]
  9. Starrenburg, M.J.; Hugenholtz, J. Citrate Fermentation by Lactococcus and Leuconostoc spp. Appl. Environm. Microbiol. 1991, 57, 3535–3540. [Google Scholar] [CrossRef] [Green Version]
  10. De Paula, A.T.; Jeronymo-Ceneviva, A.B.; Todorov, S.D.; Penna, A.L.B. The two faces of Leuconostoc mesenteroides in food systems. Food Rev. Int. 2015, 31, 147–171. [Google Scholar] [CrossRef]
  11. Stiles, M.E. Bacteriocins produced by Leuconostoc species. J. Dairy Sci. 1994, 77, 2718–2724. [Google Scholar] [CrossRef]
  12. Arqués, J.L.; Rodríguez, E.; Langa, S.; Landete, J.M.; Medina, M. Antimicrobial activity of lactic acid bacteria in dairy products and gut: Effect on pathogens. BioMed Res. Int. 2015, 584183. [Google Scholar] [CrossRef]
  13. Thangavel, G.; Subramaniyam, T. Antimicrobial Efficacy of Leuconostoc spp. Isolated from Indian Meat against Escherichia coli and Listeria monocytogenes in Spinach Leaves. Food Sci. Anim. Resour. 2019, 39, 677–685. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  14. Deegan, L.H.; Cotter, P.D.; Hill, C.; Ross, P. Bacteriocins: Biological tools for bio-preservation and shelf-life extension. Int. Dairy J. 2006, 16, 1058–1071. [Google Scholar] [CrossRef]
  15. Terzić-Vidojević, A.; Veljović, K.; Tolinački, M.; Živković, M.; Lukić, J.; Lozo, J.; Fira, Đ.; Jovčić, B.; Strahinić, I.; Begović, J.; et al. Diversity of non-starter lactic acid bacteria in autochthonous dairy products from Western Balkan Countries—Technological and probiotic properties. Food Res. Int. 2020, 136, 109494. [Google Scholar] [CrossRef]
  16. Guerrero, L.; Guàrdia, M.D.; Xicola, J.; Verbeke, W.; Vanhonacker, F.; Zakowska-Biemans, S.; Sajdakowska, M.; Sulmont-Rossé, C.; Issanchou, S.; Contel, M.; et al. Consumer-driven definition of traditional food products and innovation in traditional foods. A qualitative cross-cultural study. Appetite 2009, 52, 345–354. [Google Scholar] [CrossRef] [PubMed]
  17. Woods, D.F.; Kozak, I.M.; Flynn, S.; O’Gara, F. The Microbiome of an Active Meat Curing Brine. Front. Microbiol. 2019, 9, 3346. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  18. Cardamone, L.; Quiberoni, A.; Mercanti, D.; Fornasari, M.; Reinheimer, J.; Guglielmotti, D.M. Adventitious dairy Leuconostoc strains with interesting technological and biological properties useful for adjunct starters. Dairy Sci. Technol. 2011, 91, 457–470. [Google Scholar] [CrossRef] [Green Version]
  19. Chun, B.H.; Kim, K.H.; Jeon, H.H.; Lee, S.H.; Jeon, C.O. Pan-genomic and transcriptomic analyses of Leuconostoc mesenteroides provide insights into its genomic and metabolic features and roles in kimchi fermentation. Sci. Rep. 2017, 7, 11504. [Google Scholar] [CrossRef] [Green Version]
  20. Frantzen, C.A.; Kot, W.; Pedersen, T.B.; Ardö, Y.M.; Broadbent, J.R.; Neve, H.; Hansen, L.H.; Dal Bello, F.; Østlie, H.M.; Kleppen, H.P.; et al. Genomic Characterization of Dairy Associated Leuconostoc Species and Diversity of Leuconostocs in Undefined Mixed Mesophilic Starter Cultures. Front. Microbiol. 2017, 8, 132. [Google Scholar] [CrossRef] [Green Version]
  21. Poulsen, V.K.; Koza, A.; Al-Nakeeb, K.; Oeregaard, G. Screening for texturing Leuconostoc and genomics behind polysaccharide production. FEMS Microbiol. Lett. 2020, 367, fnaa179. [Google Scholar] [CrossRef]
  22. Pedersen, T.B.; Kot, W.P.; Hansen, L.H.; Sørensen, S.J.; Broadbent, J.R.; Vogensen, F.K.; Ardö, Y. Genome Sequence of Leuconostoc mesenteroides subsp. cremoris Strain T26, Isolated from Mesophilic Undefined Cheese Starter. Genome Announc. 2014, 2, e00485-14. [Google Scholar]
  23. Zhang, W.; Liu, W.; Song, Y.; Xu, H.; Menghe, B.; Zhang, H.; Sun, Z. Multilocus sequence typing of a dairy-associated Leuconostoc mesenteroides population reveals clonal structure with intragenic homologous recombination. J. Dairy Sci. 2015, 98, 2284–2293. [Google Scholar] [CrossRef]
  24. Sharma, A.; Kaur, J.; Lee, S.; Park, Y.S. Analysis of Leuconostoc citreum strains using multilocus sequence typing. Food Sci. Biotechnol. 2018, 27, 1755–1760. [Google Scholar] [CrossRef]
  25. Chen, J.; Lv, H.; Zhang, Z.; Zhang, H.; Zhang, B.; Wang, X.; Liu, Y.; Zhang, M.; Pang, H.; Qin, G.; et al. Multilocus Sequence Typing of Leuconostoc mesenteroides Strains from the Qinghai-Tibet Plateau. Front. Microbiol. 2021, 12, 614286. [Google Scholar] [CrossRef]
  26. Campedelli, I.; Flórez, A.B.; Salvetti, E.; Delgado, S.; Orrù, L.; Cattivelli, L.; Alegría, Á.; Felis, G.E.; Torriani, S.; Mayo, B. Draft Genome Sequence of Three Antibiotic-Resistant Leuconostoc mesenteroides Strains of Dairy Origin. Genome Announc. 2015, 3, e01018-15. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  27. Park, G.S.; Hong, S.J.; Jung, B.K.; Lee, C.; Park, C.K.; Shin, J.H. The complete genome sequence of a lactic acid bacterium Leuconostoc mesenteroides ssp. dextranicum strain DSM 20484(T). J. Biotech. 2016, 219, 3–4. [Google Scholar] [CrossRef]
  28. O’Donnell, S.T.; Ross, R.P.; Stanton, C. The Progress of Multi-Omics Technologies: Determining Function in Lactic Acid Bacteria Using a Systems Level Approach. Front. Microbiol. 2020, 28, 3084. [Google Scholar] [CrossRef] [PubMed]
  29. Franz, E.; Gras, L.M.; Dallman, T. Significance of whole genome sequencing for surveillance, source attribution and microbial risk assessment of foodborne pathogens. Curr. Opin. Food Sci. 2016. [Google Scholar] [CrossRef]
  30. Martinovic, A.; Narvhus, J.; Abrahamsen, R.K.; Ostlie, H.M.; Skeie, S.B. Application of indigenous strains of lactic acid bacteria for semi-industrial production of autochthonous Montenegrin Njeguši cheese. Int. J. Dairy Technol. 2018, 71, 1–10. [Google Scholar] [CrossRef]
  31. De Bruyne, K.; Slabbinck, B.; Waegeman, W.; Vauterin, P.; De Baets, B.; Vandamme, P. Bacterial species identification from MALDI-TOF mass spectra through data analysis and machine learning. Syst. Appl. Microbiol. 2011, 34, 20–29. [Google Scholar] [CrossRef] [PubMed]
  32. Bojanic Rasovic, M.; Mayrhofer, S.; Martinovic, A.; Dürr, K.; Domig, K.J. Lactococci of Local Origin as Potential Starter Cultures for Traditional Montenegrin Cheese Production. Food Technol. Biotechnol. 2017, 55, 55–66. [Google Scholar] [CrossRef] [PubMed]
  33. Veskovic-Moracanin, S.; Borovic, B.; Velebit, B. Morphological and biochemical characteristics of natural isolates of lactic acid bacteria isolated from Zlatar cheese. Tehnol. Mesa 2013, 54, 79–84. [Google Scholar] [CrossRef] [Green Version]
  34. Martinović, A.; Radulović, Z.; Wind, A.; Janzen, T.; Obradović, D. Isolation and characterization of bacterial flora from farmhouse fermented milk products of Serbia and Montenegro. Acta Vet. 2005, 55, 307–318. [Google Scholar]
  35. European Food Safety Authority (EFSA) Panel on Additives and Products or Substances used in Animal Feed (FEEDAP). Guidance on the assessment of bacterial susceptibility to antimicrobials of human and veterinary importance. EFSA J. 2012, 10, 2740–2750. [Google Scholar]
  36. Flórez, A.B.; Campedelli, I.; Delgado, S.; Alegría, Á.; Salvetti, E.; Felis, G.E.; Mayo, B.; Torriani, S. Antibiotic Susceptibility Profiles of Dairy Leuconostoc, Analysis of the Genetic Basis of Atypical Resistances and Transfer of Genes In Vitro and in a Food Matrix. PLoS ONE 2016, 11, e0145203. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  37. Bankevich, A.; Nurk, S.; Antipov, D.; Gurevich, A.A.; Dvorkin, M.; Kulikov, A.S.; Lesin, V.M.; Nikolenko, S.I.; Pham, S.; Prjibelski, A.D.; et al. SPAdes: A new genome assembly algorithm and its applications to single-cell sequencing. J. Comput. Biol. 2012, 19, 455–477. [Google Scholar] [CrossRef] [Green Version]
  38. Meier-Kolthoff, J.P.; Göker, M. TYGS is an automated high-throughput platform for state-of-the-art genome-based taxonomy. Nat. Commun. 2019, 10, 2182. [Google Scholar] [CrossRef]
  39. Ondov, B.D.; Treangen, T.J.; Mallonee, A.B.; Bergman, N.H.; Koren, S.; Phillippy, A.M. Fast genome and metagenome distance estimation using MinHash. bioRxiv 2015. [Google Scholar] [CrossRef] [Green Version]
  40. Jolley, K.A.; Bliss, C.M.; Bennett, J.S.; Bratcher, H.B.; Brehony, C.; Colles, F.M.; Wimalarathna, H.; Harrison, O.B.; Sheppard, S.K.; Cody, A.J.; et al. Ribosomal multilocus sequence typing: Universal characterization of bacteria from domain to strain. Microbiology 2012, 158, 1005–1015. [Google Scholar] [CrossRef]
  41. Jain, C.; Rodriguez-R, L.M.; Phillippy, A.M.; Konstantinidis, K.T.; Aluru, S. High throughput ANI analysis of 90K prokaryotic genomes reveals clear species boundaries. Nat. Comm. 2018, 9, 5114. [Google Scholar] [CrossRef] [Green Version]
  42. Van Heel, A.J.; De Jong, A.; Song, C.; Viel, J.H.; Kok, J.; Kuipers, O.P. BAGEL4: A user-friendly Web server to thoroughly mine RiPPs and bacteriocins. Nucleic Acids Res. 2018, 46, W278–W281. [Google Scholar] [CrossRef]
  43. Blin, K.; Shaw, S.; Kautsar, S.A.; Medema, M.H.; Weber, T. The antiSMASH database version 3: Increased taxonomic coverage and new query features for modular enzymes. Nucleic Acids Res. 2021, 49, D639–D643. [Google Scholar] [CrossRef]
  44. Cosentino, S.; Voldby Larsen, M.; Møller Aarestrup, F.; Lund, O. PathogenFinder—Distinguishing Friend from Foe Using Bacterial Whole Genome Sequence Data. PLoS ONE 2013, 8, e77302. [Google Scholar] [CrossRef]
  45. Carattoli, A.; Zankari, E.; García-Fernández, A.; Voldby Larsen, M.; Lund, O.; Villa, L.; Møller Aarestrup, F.; Hasman, H. In silico detection and typing of plasmids using PlasmidFinder and plasmid multilocus sequence typing. Antimicrob. Agents Chemother. 2014, 58, 3895–3903. [Google Scholar] [CrossRef] [Green Version]
  46. Joensen, K.G.; Scheutz, F.; Lund, O.; Hasman, H.; Kaas, R.S.; Nielsen, E.M.; Aarestrup, F. Real-time whole-genome sequencing for routine typing, surveillance, and outbreak detection of verotoxigenic Escherichia coli. J. Clin. Micobiol. 2014, 52, 1501–1510. [Google Scholar] [CrossRef] [Green Version]
  47. Bortolaia, V.; Kaas, R.S.; Ruppe, E.; Roberts, M.C.; Schwarz, S.; Cattoir, V.; Philippon, A.; Allesoe, R.L.; Rebelo, A.R.; Florensa, A.F.; et al. ResFinder 4.0 for predictions of phenotypes from genotypes. J. Antimicrob. Chemother. 2020, 75, 3491–3500. [Google Scholar] [CrossRef]
  48. Alcock, B.P.; Raphenya, A.R.; Lau, T.; Tsang, K.K.; Bouchard, M.; Edalatmand, A.; Huynh, W.; Nguyen, A.V.; Cheng, A.A.; Liu, S.; et al. CARD 2020: Antibiotic resistome surveillance with the comprehensive antibiotic resistance database. Nucleic Acids Res. 2020, 48, D517–D525. [Google Scholar] [CrossRef]
  49. Hyatt, D.; Chen, G.L.; Locascio, P.F.; Land, M.L.; Larimer, F.W.; Hauser, L.J. Prodigal: Prokaryotic gene recognition and translation initiation site identification. BMC Bioinform. 2010, 11, 119. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  50. Emms, D.M.; Kelly, S. OrthoFinder: Solving fundamental biases in whole genome comparisons dramatically improves orthogroup inference accuracy. Genome Biol. 2015, 16, 157. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  51. Zhang, Z.; Schwartz, S.; Wagner, L.; Miller, W. A greedy algorithm for aligning DNA sequences. J. Comput. Biol. 2000, 7, 203–214. [Google Scholar] [CrossRef] [PubMed]
  52. Martinović, A.; Mirecki, S. Food, nutrition, and health in Montenegro. In Nutritional and Health Aspects of Food in the Balkans; Lelieveld, H., Prakash, V., Prakash, J., Van der Meulen, B., Eds.; Elsevier: Amsterdam, The Netherlands, 2021; pp. 165–185. [Google Scholar]
  53. Devirgiliis, C.; Zinno, P.; Perozzi, G. Update on antibiotic resistance in foodborne Lactobacillus and Lactococcus species. Front. Microbiol. 2013, 4, 301. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  54. EFSA. Scientific opinion of the panel on biological hazards on the request from EFSA on the maintenance of the list of QPS microorganisms intentionally added to food or feed. EFSA J. 2008, 928, 1–48. [Google Scholar]
  55. Menegueti, M.G.; Gaspar, G.G.; Laus, A.M.; Basile-Filho, A.; Bellissimo-Rodrigues, F.; Auxiliadora-Martins, M. Bacteremia by Leuconostoc mesenteroides in an immunocompetent patient with chronic Chagas disease: A case report. BMC Infect Dis. 2018, 18, 547. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  56. Salvetti, E.; Campedelli, I.; Larini, I.; Conedera, G.; Torriani, S. Exploring Antibiotic Resistance Diversity in Leuconostoc spp. by a Genome-Based Approach: Focus on the lsaA Gene. Microorganisms 2021, 9, 491. [Google Scholar] [CrossRef]
  57. Schmidt, C.; Löffler, B.; Ackermann, G. Antimicrobial phenotypes and molecular basis in clinical strains of Clostridium difficile. Diagn. Microbiol. Infect. Dis. 2007, 59, 1–5. [Google Scholar] [CrossRef]
  58. Kaushal, G.; Singh, S.P. Comparative genome analysis provides shreds of molecular evidence for reclassification of Leuconostoc mesenteroides MTCC 10508 as a strain of Leu. suionicum. Genomics 2020, 112, 4023–4031. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Type Strain Genome Server analysis (TYGS) of all 16 Montenegrin brine cheese isolates and Leuconostoc sp. type strains available from the TYGS database.
Figure 1. Type Strain Genome Server analysis (TYGS) of all 16 Montenegrin brine cheese isolates and Leuconostoc sp. type strains available from the TYGS database.
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Figure 2. Minimum spanning tree (MST) based on cgMLST analysis of 88 Ln. mesenteroides isolates derived from GenBank and Montenegrin brine cheeses. Numbers on connection lines represent allelic differences between isolates. Isolates are colored according to their country of origin.
Figure 2. Minimum spanning tree (MST) based on cgMLST analysis of 88 Ln. mesenteroides isolates derived from GenBank and Montenegrin brine cheeses. Numbers on connection lines represent allelic differences between isolates. Isolates are colored according to their country of origin.
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Figure 3. Schematic presentation of present (light colors) and absent (black) orthologous groups as determined by Orthofinder analysis and the cit operon (green) in Montenegrin brine cheese isolates.
Figure 3. Schematic presentation of present (light colors) and absent (black) orthologous groups as determined by Orthofinder analysis and the cit operon (green) in Montenegrin brine cheese isolates.
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Table
Table 1. Data on origin, subspecies, growth, and biochemical parameters of the investigated Ln. mesenteroides strains. (nd) not done, (pg) poor growth, (cfu) colony forming units, (P) producer, (Cat) catalase ( Microorganisms 09 01612 i001) pH decrease wo/w 1% lactose, ( Microorganisms 09 01612 i002) pH increase wo/w 1% lactose, ( Microorganisms 09 01612 i003) cit operon positive strains, ( Microorganisms 09 01612 i004) no growth in minimum conditions, ( Microorganisms 09 01612 i005) growth in minimum and/or maximum conditions.
Table 1. Data on origin, subspecies, growth, and biochemical parameters of the investigated Ln. mesenteroides strains. (nd) not done, (pg) poor growth, (cfu) colony forming units, (P) producer, (Cat) catalase ( Microorganisms 09 01612 i001) pH decrease wo/w 1% lactose, ( Microorganisms 09 01612 i002) pH increase wo/w 1% lactose, ( Microorganisms 09 01612 i003) cit operon positive strains, ( Microorganisms 09 01612 i004) no growth in minimum conditions, ( Microorganisms 09 01612 i005) growth in minimum and/or maximum conditions.
PCheese
ID		Strain IDSubsp.-IdGramCatEPSCO2pH Growth Medium after (h) wo/w 1% LactoseCfu/g CheeseGrowth with % NaClGrowth °C
TYGS(4 h)(6 h)(8 h)(24 h)(48 h)2%3%4.5%6.5%410153045
A2-1406INF2Ln. m. cremoris?+--+6.6/6.46.6/6.46.5/5.85.8/4.64.8/4.489+pg---+++-
3-1406INF3bLn. m. mesenteroides+--+6.6/6.46.6/6.46.6/5.25.9/4.45.3/4.439+pg--++++- (+)
B1-1404INF36Ln. m. mesenteroides+--+6.5/6.76.4/6.66.4/5.85.8/5.05.3/4.658++++++++- (+)
2-1404INF38Ln. m. mesenteroides+--+6.5/6.56.4/6.36.4/6.15.9/5.25.8/4.961+++--+++-
C1453INF46Ln. m. mesenteroides+--+6.4/6.66.4/6.66.0/6.15.7/5.45.4/4.741+++++++++
D1-3763INF82aLn. m. dextranicum+--+ndndndndndndndndndndndndndndnd
INF82bLn. m. mesenteroides+--+5.5/5.85.4/5.75.3/5.55.2/5.45.1/5.372-pg+pg-++++
3-3763INF90Ln m. mesenteroides+--+5.8/6.05.9/5.85.8/5.45.7/5.35.7/5.153++++-++++
INF92Ln. m. mesenteroides+---6.1/5.96.0/5.86.0/5.75.8/5.65.6/5.173-++pg-++++
INF94Ln. m. mesenteroides+---5.7/6.05.7/5.75.6/5.45.4/5.25.2/5.247++pgpg-+-+-
4-3763INF98Ln. m. cremoris?+--+5.4/6.05.4/5.95.4/5.85.2/5.85.2/5.563+++pg-++++
E4-3758INF103Ln. m. mesenteroides+---5.4/5.55.2/5.55.2/5.55.1/5.35.0/5.289++pgpg--+++
F4-14246INF117Ln. m. jonggajibkimchii?+--+6.0/6.25.9/5.75.9/5.75.8/5.65.7/5.592-pg++-++++
GŽINF 131Ln. m. dextranicum+--+5.6/6.45.3/6.34.6/6.24.3/4.64.2/4.472++++-+++-
H3-1387INF157Ln. m. mesenteroides+--+6.4/6.66.3/6.66.2/5.85.8/5.55.4/4.941++++-++++
I4-1383INF166Ln. m. jonggajibkimchii?+--+6.7/6.46.5/6.45.8/5.95.1/4.64.8/4.442+++--+++-
Table
Table 2. Genes of the bacteriocin gene cluster and biosynthesis of secondary metabolites identified by BAGEL4 and AntiSMASH.
Table 2. Genes of the bacteriocin gene cluster and biosynthesis of secondary metabolites identified by BAGEL4 and AntiSMASH.
Isolate-IDBacteriocinBetalactoneT3PKSOther
INF2IIc++Enterocin_x_chain_beta
INF3bIIc, MesentericinY105-+Enterocin_x_chain_beta
INF36IIc++Enterocin_x_chain_beta
INF38IIc++Enterocin_x_chain_beta
INF46IIc++Enterocin_x_chain_beta
INF82aIIc++Enterocin_x_chain_beta
INF90IIc+
LomaiviticinA//C-E		+Enterocin_x_chain_beta
INF82bIIcLomaiviticinA//C-E+Enterocin_x_chain_beta
INF94IIcLomaiviticinA//C-E+Enterocin_x_chain_beta
INF92IIc-+Enterocin_x_chain_beta
INF117IIc-+-
INF103IIc-+-
INF98IIc-+Enterocin_x_chain_beta
INF131MesentericinB105++Enterocin_x_chain_beta
INF157IIc-+Enterocin_x_chain_beta
INF166-++-
Table
Table 3. AMR targets, virulence genes, plasmids, pathogenicity, (S) susceptible, (Ery) erythromycin, (Amp) ampicillin, (Pen) penicillin, (Inhz) inhibition zone, (-) negative, and (nd) not done.
Table 3. AMR targets, virulence genes, plasmids, pathogenicity, (S) susceptible, (Ery) erythromycin, (Amp) ampicillin, (Pen) penicillin, (Inhz) inhibition zone, (-) negative, and (nd) not done.
Strain IDAMRPlasmid FinderVirulence FinderPathogen Finder
CARDResFinderSusceptibility Testing
INF2--ndRep3--
INF3b--ndRep3--
INF36Clostridioides difficile 23S rRNA with C656T mutation conferring resistance to erythromycin and clindamycin, 98.97% identity, 10.00% coverage-S
Ery (15 µg)
Inhz 26 mm		---
INF38--nd---
INF46--nd---
INF82a--nd---
INF82b--nd---
INF90--nd---
INF92--ndRep3--
INF94--nd---
INF98--ndRep3--
INF103--nd---
INF11797.5% identity to blaTEM 33, 55.94% coverage
(using loose criteria)		beta lactam resistance
99.04% identity to blaTEM 141, 60.51% coverage		S
Amp (10 µg)
Inhz 19.5 mm
Pen (1U)
Inhz 21 mm		---
INF131--nd---
INF157--nd---
INF166--ndRepA_N--
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Ruppitsch, W.; Nisic, A.; Hyden, P.; Cabal, A.; Sucher, J.; Stöger, A.; Allerberger, F.; Martinović, A. Genetic Diversity of Leuconostoc mesenteroides Isolates from Traditional Montenegrin Brine Cheese. Microorganisms 2021, 9, 1612. https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9081612

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Ruppitsch W, Nisic A, Hyden P, Cabal A, Sucher J, Stöger A, Allerberger F, Martinović A. Genetic Diversity of Leuconostoc mesenteroides Isolates from Traditional Montenegrin Brine Cheese. Microorganisms. 2021; 9(8):1612. https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9081612

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Ruppitsch, Werner, Andjela Nisic, Patrick Hyden, Adriana Cabal, Jasmin Sucher, Anna Stöger, Franz Allerberger, and Aleksandra Martinović. 2021. "Genetic Diversity of Leuconostoc mesenteroides Isolates from Traditional Montenegrin Brine Cheese" Microorganisms 9, no. 8: 1612. https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9081612

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