Microorganisms

Research

18 pages, 1633 KiB

Open AccessArticle

Presence of Listeria monocytogenes in Ready-to-Eat Artisanal Chilean Foods

by Fernanda Bustamante, Eduard Maury-Sintjago, Fabiola Cerda Leal, Sergio Acuña, Juan Aguirre, Miriam Troncoso, Guillermo Figueroa and Julio Parra-Flores

Microorganisms 2020, 8(11), 1669; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8111669 - 27 Oct 2020

Cited by 10 | Viewed by 3649

Abstract

Ready-to-eat (RTE) artisanal foods are very popular, but they can be contaminated by Listeria monocytogenes. The aim was to determine the presence of L. monocytogenes in artisanal RTE foods and evaluate its food safety risk. We analyzed 400 RTE artisanal food samples [...] Read more.

Ready-to-eat (RTE) artisanal foods are very popular, but they can be contaminated by Listeria monocytogenes. The aim was to determine the presence of L. monocytogenes in artisanal RTE foods and evaluate its food safety risk. We analyzed 400 RTE artisanal food samples requiring minimal (fresh products manufactured by a primary producer) or moderate processing (culinary products for sale from the home, restaurants such as small cafés, or on the street). Listeria monocytogenes was isolated according to the ISO 11290-1:2017 standard, detected with VIDAS equipment, and identified by real-time polymerase chain reaction (PCR). A small subset (n = 8) of the strains were further characterized for evaluation. The antibiotic resistance profile was determined by the CLSI methodology, and the virulence genes hlyA, prfA, and inlA were detected by PCR. Genotyping was performed by pulsed-field gel electrophoresis (PFGE). Listeria monocytogenes was detected in 7.5% of RTE artisanal foods. On the basis of food type, positivity in minimally processed artisanal foods was 11.6%, significantly different from moderately processed foods with 6.2% positivity (p > 0.05). All the L. monocytogenes strains (n = 8) amplified the three virulence genes, while six strains exhibited premature stop codons (PMSC) in the inlA gene; two strains were resistant to ampicillin and one strain was resistant to sulfamethoxazole-trimethoprim. Seven strains were 1/2a serotype and one was a 4b strain. The sampled RTE artisanal foods did not meet the microbiological criteria for L. monocytogenes according to the Chilean Food Sanitary Regulations. The presence of virulence factors and antibiotic-resistant strains make the consumption of RTE artisanal foods a risk for the hypersensitive population that consumes them. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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12 pages, 811 KiB

Open AccessArticle

Analysis of the Bacterial Diversity of Paipa Cheese (a Traditional Raw Cow’s Milk Cheese from Colombia) by High-Throughput Sequencing

by José Castellanos-Rozo, Rubén Pérez Pulido, Mª. José Grande, Rosario Lucas and Antonio Gálvez

Microorganisms 2020, 8(2), 218; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8020218 - 06 Feb 2020

Cited by 16 | Viewed by 3245

Abstract

Background: Paipa cheese is a traditional, semi-ripened cheese made from raw cow’s milk in Colombia. The aim of this work was to gain insights on the microbiota of Paipa cheese by using a culture-independent approach. Method: two batches of Paipa cheese from three [...] Read more.

Background: Paipa cheese is a traditional, semi-ripened cheese made from raw cow’s milk in Colombia. The aim of this work was to gain insights on the microbiota of Paipa cheese by using a culture-independent approach. Method: two batches of Paipa cheese from three formal producers were sampled during ripening for 28 days. Total DNA from the cheese samples was used to obtain 16S rRNA gene sequences by using Illumina technology. Results: Firmicutes was the main phylum found in the cheeses (relative abundances: 59.2–82.0%), followed by Proteobacteria, Actinobacteria and Bacteroidetes. Lactococcus was the main genus, but other lactic acid bacteria (Enterococcus, Leuconostoc and Streptococcus) were also detected. Stapylococcus was also relevant in some cheese samples. The most important Proteobacteria were Enterobacteriaceae, Aeromonadaceae and Moraxellaceae. Enterobacter and Enterobacteriaceae (others) were detected in all cheese samples. Serratia and Citrobacter were detected in some samples. Aeromonas and Acinetobacter were also relevant. Other minor genera detected were Marinomonas, Corynebacterium 1 and Chryseobacterium. The principal coordinates analysis suggested that there were producer-dependent differences in the microbiota of Paipa cheeses. Conclusions: lactic acid bacteria are the main bacterial group in Paipa cheeses. However, other bacterial groups, including spoilage bacteria, potentially toxin producers, and bacteria potentially pathogenic to humans and/or prone to carry antimicrobial resistance genes are also relevant in the cheeses. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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8 pages, 553 KiB

Open AccessArticle

Absence of Viable Toxoplasma gondii in Artisanal Raw-Milk Ewe Cheese Derived from Naturally Infected Animals

by David Ranucci, Elena Battisti, Fabrizia Veronesi, Manuela Diaferia, Giulia Morganti, Raffaella Branciari, Ezio Ferroglio, Andrea Valiani and Francesco Chiesa

Microorganisms 2020, 8(1), 143; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8010143 - 20 Jan 2020

Cited by 9 | Viewed by 3706

Abstract

The presence of viable Toxoplasma gondii was investigated in artisanal cheeses made from milk of naturally infected ewes. Ewe milk was analyzed beforehand for the presence and vitality of T. gondii by loop-mediated isothermal amplification (LAMP) and reverse-transcriptase PCR (RT-PCR), respectively. Cheeses were [...] Read more.

The presence of viable Toxoplasma gondii was investigated in artisanal cheeses made from milk of naturally infected ewes. Ewe milk was analyzed beforehand for the presence and vitality of T. gondii by loop-mediated isothermal amplification (LAMP) and reverse-transcriptase PCR (RT-PCR), respectively. Cheeses were prepared from raw milk following a traditional cheesemaking process. The cheese obtained from T. gondii-positive milk was analyzed by LAMP to detect Toxoplasma DNA-positive samples. RT-PCR was then carried out to assess the viability of the parasites in T. gondii-positive milk samples and fresh cheese, after 5 and 15 days of ripening. Physical-chemical parameters of cheeses were also investigated. All cheese samples derived from T. gondii-positive milk were positive according to LAMP, at both 5 and 15 days of ripening, while none of the samples were positive according to RT-PCR. Thus, while the presence of the parasite was demonstrated by the detection of specific DNA, the absence of detectable T. gondii RNA supports the hypothesis that changes in the chemical and physical characteristics occurring during the cheesemaking process and ripening period, could be sufficient to inactivate viable T. gondii in milk, minimizing the risk of human infection through consumption of raw sheep milk cheese. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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13 pages, 1755 KiB

Open AccessArticle

Phenotypic Diversity of Lactobacillus casei Group Isolates as a Selection Criterion for Use as Secondary Adjunct Starters

by Alessia Levante, Elena Bancalari, Martina Tambassi, Camilla Lazzi, Erasmo Neviani and Monica Gatti

Microorganisms 2020, 8(1), 128; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8010128 - 17 Jan 2020

Cited by 13 | Viewed by 3156

Abstract

Autochthonous lactic acid bacteria (LAB) play a key role in the development of cheese flavor. As the pasteurization treatment on raw milk causes the elimination of LAB, secondary starter cultures are used in cheese manufacture to obtain cheeses with improved and standardized flavors. [...] Read more.

Autochthonous lactic acid bacteria (LAB) play a key role in the development of cheese flavor. As the pasteurization treatment on raw milk causes the elimination of LAB, secondary starter cultures are used in cheese manufacture to obtain cheeses with improved and standardized flavors. In this work, strains of the L. casei group isolated from traditional Italian cheeses were screened for their phenotypic features of technological interest for use as secondary starters. Their milk acidifying performance and the production of volatile compounds when grown in milk were evaluated. Simultaneously, the acetoin metabolic pathway presence was screened in the strains and assessed for its transcriptional activation. The results showed that the analyzed strains, despite belonging to taxonomically-related species, vary greatly according to the measured phenotypes. Four strains among the fourteen screened could be potentially used as adjunct cultures for cheese-making processes. The strain that showed the highest production of acetoin upregulated the aspartate pathway. An increased knowledge of volatile compounds’ production and acidifying properties of LAB strains isolated from traditional dairy products might guide the selection of strains for industrial applications. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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13 pages, 3279 KiB

Open AccessArticle

Peruvian chicha: A Focus on the Microbial Populations of This Ancient Maize-Based Fermented Beverage

by Daniela Bassi, Luigi Orrù, Jeison Cabanillas Vasquez, Pier Sandro Cocconcelli and Cecilia Fontana

Microorganisms 2020, 8(1), 93; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8010093 - 10 Jan 2020

Cited by 24 | Viewed by 4607

Abstract

Peruvian chicha de jora is one of the most ancient traditional beverages produced through maize fermentation, still popular to modern consumers, but less studied in terms of microbial compositions. In this work, the bacterial biodiversity of 27 chicha samples collected from 14 different [...] Read more.

Peruvian chicha de jora is one of the most ancient traditional beverages produced through maize fermentation, still popular to modern consumers, but less studied in terms of microbial compositions. In this work, the bacterial biodiversity of 27 chicha samples collected from 14 different “chicherias” in seven provinces of Peru was investigated by Next-Generation Sequencing (NGS). A large dissimilarity in chicha microbial composition was a direct consequence of ingredients, manufacturing processes and geographical influences. The core microbiome was represented by six main genera, belonging to Lactic Acid Bacteria (LAB) and Acetic Acid Bacteria (AAB). Lactobacillus prevailed (more than 50% of sequences belong to this genus) followed by Weissella, Leuconostoc, Lactococcus and Streptococcus. Acetobacter was the only AAB genus identified in chicha. The occurrence of sequences associated to spoiling and pathogenic bacteria, such as Bacillus, Clostridium, and Enterobacteriaceae, was observed only in a few samples, validating the safety of this beverage. Predictive functional annotation of metagenomic sequences revealed that carbohydrate and amino acid metabolisms and coenzyme transport are the main KEGG categories associated to chicha fermentation pathways. The old recipes and traditional processing of each chicherias helps maintain native microorganisms as a resource of biodiversity with potential technological and health-beneficial properties. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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22 pages, 3611 KiB

Open AccessArticle

Piacentinu Ennese PDO Cheese as Reservoir of Promising Probiotic Bacteria

by Alessandra Pino, Nunziatina Russo, Koenraad Van Hoorde, Maria De Angelis, Giuseppe Sferrazzo, Cinzia Lucia Randazzo and Cinzia Caggia

Microorganisms 2019, 7(8), 254; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms7080254 - 12 Aug 2019

Cited by 29 | Viewed by 4224

Abstract

Piacentinu Ennese is a protected designation of origin (PDO) cheese produced in the surrounding area of Enna (Sicily, Italy), using raw ewe’s milk without the addition of any starter cultures. In the present study, the Lactobacillus population of Piacentinu Ennese PDO cheese was [...] Read more.

Piacentinu Ennese is a protected designation of origin (PDO) cheese produced in the surrounding area of Enna (Sicily, Italy), using raw ewe’s milk without the addition of any starter cultures. In the present study, the Lactobacillus population of Piacentinu Ennese PDO cheese was in vitro screened in order to select promising probiotic strains to be further used in humans. One hundred and sixty-nine lactic acid bacteria (LAB) were isolated from 90 days ripened cheeses and identified by Rep-PCR genomic fingerprinting, using the (GTG)₅-primer, and by MALDI-TOF MS. One hundred and thirteen (113) isolates belonging to QPS-list species were characterized for both safety and functional properties. All tested isolates were considered safe because none showed either gelatinase, DNase, mucinase, or hemolytic activity. Tolerance to lysozyme, bile salts, and acidic conditions, along with ability to survive under simulated gastrointestinal digestion, were observed. In addition, based on antimicrobial activity against pathogens, cell surface characteristics, Caco-2 adhesion abilities, and anti-inflammatory potential, it was possible to confirm the strain-dependent functional aptitude, suggesting that Piacentinu Ennese PDO cheese may be considered a precious source of probiotic candidates. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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Review

Jump to: Research, Other

24 pages, 1128 KiB

Open AccessReview

Microbial Safety of Milk Production and Fermented Dairy Products in Africa

by James Owusu-Kwarteng, Fortune Akabanda, Dominic Agyei and Lene Jespersen

Microorganisms 2020, 8(5), 752; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8050752 - 17 May 2020

Cited by 65 | Viewed by 10139

Abstract

In Africa, milk production, processing and consumption are integral part of traditional food supply, with dairy products being a staple component of recommended healthy diets. This review provides an overview of the microbial safety characteristics of milk production and fermented dairy products in [...] Read more.

In Africa, milk production, processing and consumption are integral part of traditional food supply, with dairy products being a staple component of recommended healthy diets. This review provides an overview of the microbial safety characteristics of milk production and fermented dairy products in Africa. The object is to highlight the main microbial food safety hazards in the dairy chain and to propose appropriate preventive and control measures. Pathogens of public health concern including Mycobacterium bovis, Brucella abortus and Coxiella burnettii, which have largely been eradicated in many developed nations, still persist in the dairy chain in Africa. Factors such as the natural antimicrobial systems in milk and traditional processing technologies, including fermentation, heating and use of antimicrobial additives, that can potentially contribute to microbial safety of milk and dairy products in Africa will be discussed. Practical approaches to controlling safety hazards in the dairy chain in Africa have been proposed. Governmental regulatory bodies need to set the necessary national and regional safety standards, perform inspections and put measures in place to ensure that the standards are met, including strong enforcement programs within smallholder dairy chains. Dairy chain actors would require upgraded knowledge and training in preventive approaches such as good agricultural practices (GAP), hazard analysis and critical control points (HACCP) design and implementation and good hygienic practices (GHPs). Food safety education programs should be incorporated into school curricula, beginning at the basic school levels, to improve food safety cognition among students and promote life-long safe food handling behaviour. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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Other

Jump to: Research, Review

9 pages, 238 KiB

Open AccessOpinion

Microbiological Safety and the Management of Microbial Resources in Artisanal Foods and Beverages: The Need for a Transdisciplinary Assessment to Conciliate Actual Trends and Risks Avoidance

by Vittorio Capozzi, Mariagiovanna Fragasso and Pasquale Russo

Microorganisms 2020, 8(2), 306; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms8020306 - 22 Feb 2020

Cited by 46 | Viewed by 4547

Abstract

Current social and environmental trends explain the rising popularity of artisanal fermented foods and beverages. In contrast with their marketing success, several studies underline a lack of regulations necessary to claim differences occurred from the farm to the fork and to certify high [...] Read more.

Current social and environmental trends explain the rising popularity of artisanal fermented foods and beverages. In contrast with their marketing success, several studies underline a lack of regulations necessary to claim differences occurred from the farm to the fork and to certify high quality and safety standards. Microbial-based fermentative processes represent the crucial phase in the production of fermented foods and beverages. Nevertheless, what are the effects of the application of the “artisanal” category to the management of food fermentations? This opinion paper is built up on this issue by analyzing microbial aspects, instances of innovation, safety issues, and possible solutions. Evidence indicates: (i) a global curiosity to exploit food fermentations as drivers of innovation in artisanal contexts and (ii) an increasing interest of the artisanal producers into management of fermentation that relies on native microbial consortia. Unfortunately, this kind of revamp of “artisanal food microbiology,” rather than re-establishing artisanal content, can restore the scarce hygienic conditions that characterized underdeveloped food systems. We highlight that in the scientific literature, it is possible to underline existing approaches that, surpassing the dichotomy between relying on spontaneous fermentation and the use of commercial starter cultures, depict a “third way” to conjugate interest in enhancing the artisanal attributes with the need for correct management of microbial-related risks in the final products. Full article

(This article belongs to the Special Issue Artisanal Foods: Challenges for Microbiological Control and Safety)

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