Special Issue "Lactic Acid Fermentation: Biotechnological Developments, Challenges, and Opportunities"

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Microbial Metabolism, Physiology & Genetics".

Deadline for manuscript submissions: closed (31 May 2021).

Special Issue Editors

Dr. Mohamed Ali Abdel-Rahman
E-Mail Website
Guest Editor
1. Al-Azhar Center of Fermentation Biotechnology and Applied Microbiology, Al-Azhar University, Cairo, Egypt
2. Laboratory of Microbial Physiology, Botany and Microbiology Department, Faculty of Science (boys), Al-Azhar University, Cairo, Egypt
Interests: lactic acid fermentation; yeast fermentation
Special Issues, Collections and Topics in MDPI journals
Dr. Luca Settanni
E-Mail Website
Guest Editor
Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy
Interests: lactic acid fermentation; yeast fermentation; microbial ecology of raw materials and fermented foods; starter selection
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Lactic acid is an important platform chemical used in various applications, including food, agriculture, cosmetics, pharmaceutical, and chemical industries. It serves as a building block for the production of polylactic acid, a biodegradable plastic polymer, which can replace traditional petroleum-based polymers and help to reduce environmental pollution. However, cost-effective production of optically pure L- and D-lactic acids is necessary to achieve quality and thermostable PLA. This Special Issue is focused on research advances for the production of optically pure L- or D-lactic acids using microbial fermentation. It covers the current challenges including utilization of polymeric sugars, utilization of cellulosic biomass and waste materials, establishing/investigating powerful microbial producers resistant to inhibitory compounds released during biomass treatments, and establishing pH- and temperature-tolerant lactic acid producing microbes, as well as challenges related to substrate or end-product inhibition, efficient utilization of mixed sugars, and bioprocess development for enhanced production by fermentation technology. We welcome manuscripts on topics including, but not limited to, the following:

  • Biomass utilization in lactic acid production;
  • Environmental wastes in lactic acid production;
  • New substrate sources;
  • Lactic acid bioprocess design;
  • Enhancement of lactic acid fermentation;
  • Developing robust lactic acid producers;
  • Recent advancements in lactic acid production;
  • Industrial production of lactic acid;
  • Strategies for adaptive control of a fermentation bioprocess.

Dr. Mohamed Ali Abdel-Rahman
Assoc. Prof. Luca Settanni
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fermentation is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • lactic acid production
  • fermentation design, polylactic acid
  • SSF
  • biorefinery
  • agricultural wastes
  • industrial wastes
  • lactic acid bacteria
  • biomass utilization
  • fermentation mode

Published Papers (6 papers)

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Research

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Article
Use of Corn-Steep Water Effluent as a Promising Substrate for Lactic Acid Production by Enterococcus faecium Strain WH51-1
Fermentation 2021, 7(3), 111; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7030111 - 08 Jul 2021
Cited by 1 | Viewed by 545
Abstract
Various challenges facing the industrial production of bio-based lactic acid (LA) such as cost of raw materials and nitrogen sources, as well as contamination risk by mesophilic and neutrophilic producers, should be overcome for the commercial production. This study aimed to investigate the [...] Read more.
Various challenges facing the industrial production of bio-based lactic acid (LA) such as cost of raw materials and nitrogen sources, as well as contamination risk by mesophilic and neutrophilic producers, should be overcome for the commercial production. This study aimed to investigate the feasibility of corn steep water (CSW) as a raw material for LA production using a newly thermo-alkali-tolerant lactic acid bacterium. The physicochemical characteristics of CSW were investigated. The high carbohydrates, proteins, amino acids, vitamins, essential elements, minerals, and non-protein nitrogenous compounds content confirmed that the CSW is a promising substrate for LA production. Out of 67 bacterial isolates, Enterococcus faecium WH51-1 was selected based on its tolerance to high temperatures and inhibitory compounds (sodium metabisulfate, sodium chloride, sodium acetate, and formic acid). Fermentation factors including sugar concentration, temperature, inoculum size, and neutralizing agents were optimized for LA production. Lactic acid concentration of about 44.6 g/L with a high yield (0.89 ± 0.02 g/g) was obtained using 60 g/L of CSW sugar, inoculum size 10% (v/v), 45 °C, and sodium hydroxide or calcium carbonate as a neutralizing agent. These results demonstrated the potential of strain WH51-1 for LA production using CSW effluent as raw material. Full article
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Article
Influence of Nitrogen Sources on D-Lactic Acid Biosynthesis by Sporolactobacillus laevolacticus DSM 442 Strain
Fermentation 2021, 7(2), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7020078 - 14 May 2021
Viewed by 723
Abstract
The purpose of this study was to explore the possibility of replacing an expensive yeast extract contained in the fermentation medium for D-lactic acid (D-LA, R-lactic acid) biosynthesis with an alternative nitrogen source. The screening studies were conducted under stationary conditions and showed [...] Read more.
The purpose of this study was to explore the possibility of replacing an expensive yeast extract contained in the fermentation medium for D-lactic acid (D-LA, R-lactic acid) biosynthesis with an alternative nitrogen source. The screening studies were conducted under stationary conditions and showed that pea seed hydrolysate was the most beneficial substrate in the process of D-LA biosynthesis by the strain Sporolactobacillus laevolacticus DSM 442 among the used inorganic and organic nitrogen sources, waste materials, food and agricultural products. After 96 h, 75.5 g/L D-LA was obtained in batch cultures in a medium containing pea seed hydrolysate, with an average productivity of 0.79 g/L/h, yield of 75.5%, and optical purity of 99.4%. In batch cultures fed once, in a medium with an analogous composition, 122.6 g/L D-LA was obtained after 120 h, and the average yield, productivity and optical purity were 87.6%, 1.021 g/L/h, and 99.6%, respectively. Moreover, the amount of D-LA obtained in the fermentation medium enriched with the above-mentioned cheap agricultural product was similar to the amounts obtained in the medium containing yeast extract in both stationary and bioreactor cultures. Our research shows that hydrolyzed pea seeds, which belong to the legume family, may be a promising nitrogen source for the production of D-LA on an industrial scale. Full article
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Article
Efficient Co-Utilization of Biomass-Derived Mixed Sugars for Lactic Acid Production by Bacillus coagulans Azu-10
Fermentation 2021, 7(1), 28; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010028 - 18 Feb 2021
Cited by 1 | Viewed by 813
Abstract
Lignocellulosic and algal biomass are promising substrates for lactic acid (LA) production. However, lack of xylose utilization and/or sequential utilization of mixed-sugars (carbon catabolite repression, CCR) from biomass hydrolysates by most microorganisms limits achievable titers, yields, and productivities for economical industry-scale production. This [...] Read more.
Lignocellulosic and algal biomass are promising substrates for lactic acid (LA) production. However, lack of xylose utilization and/or sequential utilization of mixed-sugars (carbon catabolite repression, CCR) from biomass hydrolysates by most microorganisms limits achievable titers, yields, and productivities for economical industry-scale production. This study aimed to design lignocellulose-derived substrates for efficient LA production by a thermophilic, xylose-utilizing, and inhibitor-resistant Bacillus coagulans Azu-10. This strain produced 102.2 g/L of LA from 104 g/L xylose at a yield of 1.0 g/g and productivity of 3.18 g/L/h. The CCR effect and LA production were investigated using different mixtures of glucose (G), cellobiose (C), and/or xylose (X). Strain Azu-10 has efficiently co-utilized GX and CX mixture without CCR; however, total substrate concentration (>75 g/L) was the only limiting factor. The strain completely consumed GX and CX mixture and homoferemnatively produced LA up to 76.9 g/L. On the other hand, fermentation with GC mixture exhibited obvious CCR where both glucose concentration (>25 g/L) and total sugar concentration (>50 g/L) were the limiting factors. A maximum LA production of 50.3 g/L was produced from GC mixture with a yield of 0.93 g/g and productivity of 2.09 g/L/h. Batch fermentation of GCX mixture achieved a maximum LA concentration of 62.7 g/L at LA yield of 0.962 g/g and productivity of 1.3 g/L/h. Fermentation of GX and CX mixture was the best biomass for LA production. Fed-batch fermentation with GX mixture achieved LA production of 83.6 g/L at a yield of 0.895 g/g and productivity of 1.39 g/L/h. Full article
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Article
Evaluating the Effect of Lignocellulose-Derived Microbial Inhibitors on the Growth and Lactic Acid Production by Bacillus coagulans Azu-10
Fermentation 2021, 7(1), 17; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010017 - 27 Jan 2021
Cited by 3 | Viewed by 1041
Abstract
Effective lactic acid (LA) production from lignocellulosic biomass materials is challenged by several limitations related to pentose sugar utilization, inhibitory compounds, and/or fermentation conditions. In this study, a newly isolated Bacillus coagulans strain Azu-10 was obtained and showed homofermentative LA production from xylose [...] Read more.
Effective lactic acid (LA) production from lignocellulosic biomass materials is challenged by several limitations related to pentose sugar utilization, inhibitory compounds, and/or fermentation conditions. In this study, a newly isolated Bacillus coagulans strain Azu-10 was obtained and showed homofermentative LA production from xylose with optimal fermentation conditions at 50 °C and pH 7.0. Growth of strain Azu-10 and LA-fermentation efficiency were evaluated in the presence of various lignocellulose-derived inhibitors (furans, carboxylic acids, and phenols) at different concentrations. Furanic lignocellulosic-derived inhibitors were completely detoxified. The strain has exhibited high biomass, complete xylose consumption, and high LA production in the presence of 1.0–4.0 g/L furfural and 1.0–5.0 g/L of hydroxymethyl furfural, separately. Moreover, strain Azu-10 exhibited high LA production in the presence of 5.0–15.0 g/L acetic acid, 5.0 g/L of formic acid, and up to 7.0 g/L of levulinic acid, separately. Besides, for phenolic compounds, p-coumaric acid was most toxic at 1.0 g/L, while syringaldehyde or p-hydroxybenzaldehyde, and vanillin at 1.0 g/L did not inhibit LA fermentation. The present study provides an interesting potential candidate for the thermophilic LA fermentation from lignocellulose-derived substrates at the industrial biorefinery level. Full article
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Article
Single and Multiple Inoculum of Lactiplantibacillus plantarum Strains in Table Olive Lab-Scale Fermentations
Fermentation 2020, 6(4), 126; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation6040126 - 18 Dec 2020
Viewed by 887
Abstract
In order to improve the olives’ quality, and to reduce the de-bittering time during the table olive fermentation process, it is necessary to pilot the fermentation by inoculating the brine with selected cultures of microorganisms. Some probiotic tests, such as resistance/sensitivity to antibiotics, [...] Read more.
In order to improve the olives’ quality, and to reduce the de-bittering time during the table olive fermentation process, it is necessary to pilot the fermentation by inoculating the brine with selected cultures of microorganisms. Some probiotic tests, such as resistance/sensitivity to antibiotics, bile salt hydrolase (BSH) activity, growth at acidic pH, an auto-aggregation assay, and a test of the production of exopolysaccharides, were carried out in order to screen 35 oleuropeinolytic Lactiplantibacillus plantarum subsp. plantarum strains to be used in guided fermentations of table olives. On the basis of the technological and probiotic screening, we analyzed the progress of three different lab-scale fermentations of Olea europaea L. Itrana cv. olives inoculated with spontaneous, single, and multiple starters: jar A was left to ferment spontaneously; jar B was inoculated with a strongly oleuropeinolytic strain (L. plantarum B1); jar C was inoculated with a multiple inoculum (L. plantarum B1 + L. plantarum B51 + L. plantarum B124). The following parameters were monitored during the fermentation: pH, titratable acidity, NaCl concentration, the degradation of bio-phenols, and the enrichment rate of hydroxytyrosol and tyrosol in the olive’s flesh, oil and brine. The degradation of secoiridoid glucosides appeared to be faster in the inoculated jars than in the spontaneously-fermented jar. The production of hydroxytyrosol and ligstroside aglycons was high. This indicated a complete degradation of the oleuropein and a partial degradation of the ligstroside. The multiple inoculum ensured a complete debittering, and could give probiotic traits. The presence of L. plantarum B1 and B124 as a fermentation starter guarantees an optimal trend of de-bittering and fermentation variables, thus ensuring the production of a better final product. L. plantarum B51 could be considered to be a promising probiotic candidate for obtaining probiotic food of completely vegetable origin. Full article
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Review

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Review
Non-Alcoholic Fermentation of Maize (Zea mays) in Sub-Saharan Africa
Fermentation 2021, 7(3), 158; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7030158 - 18 Aug 2021
Cited by 1 | Viewed by 393
Abstract
Maize, together with its fermented products, is fundamental for human nutrition and animal feed globally. Non-alcoholic fermentation of maize using lactic acid bacteria (LAB) is one of the food preservation methods that has been utilised throughout the centuries and has played a vital [...] Read more.
Maize, together with its fermented products, is fundamental for human nutrition and animal feed globally. Non-alcoholic fermentation of maize using lactic acid bacteria (LAB) is one of the food preservation methods that has been utilised throughout the centuries and has played a vital role in the manufacturing of many fermented beverages consumed these days. However, the coincidence of LAB and yeasts during the spontaneous fermentation of maize-based products is inevitable. The involvement of other microorganisms such as moulds, Bacillus species and acetic acid bacteria in the fermentation of maize is important to the characteristics of the final product. Fermented beverages are affordable, have been produced traditionally and are known for their organoleptic properties, as well as their health-promoting compounds. The consumption of non-alcoholic beverages has the prospect of reducing the detrimental health and economic effects of a poor diet. Different fermented maize-based gruels and beverages such as ogi, mawe, banku and kenkey in West Africa, togwa in East Africa, as well as mahewu in South Africa have been documented. The physical and biochemical properties of most of these maize-based fermented products have been investigated and modified by various researchers. Attempts to enhance the nutritional properties of these products rely on supplementation with legumes to supply the insufficient amino acids. The production technology of these products has evolved from traditional to industrial production in recent years. Full article
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