Improvement of Lactobacillus brevis NM101-1 grown on sugarcane molasses for mannitol, lactic and acetic acid production

Selective influence of garlic as a key ingredient in kimchi on lactic acid bacteria in a fermentation model system

Garlic is an essential ingredient added to kimchi, a fermented vegetable, in small amounts owing to its sensory and antibacterial properties. This study aimed to elucidate the complex relationship between garlic and specific lactic acid bacteria (LAB) and the resulting metabolite changes in a controlled kimchi model system using nine strains as mixed and individual starters. The group without garlic using mixed starters showed the highest LAB growth activity, which influenced lactic acid production, pH, and titratable acidity. The group without garlic also showed differences in the composition of bacteria, such as Latilactobacillus sakei, Levilactobacillus brevis, unclassified Leuconostoc, and Weissella koreensis, during the fermentation period. In addition, the altering patterns of metabolites in the group without garlic during fermentation differed from those in the group with garlic. In addition, the metabolic profile of L. brevis group was mostly different from that of the other strains in the controlled model kimchi system using individual starters, suggesting that changes in LAB composition by garlic could subsequently affect metabolites during fermentation. This study provides valuable insights into the complex interactions among food ingredients, LAB succession, and metabolite production during fermentation.

Enhanced antimicrobial activity of lactic acid bacteria through genome shuffling and genetic variability among shuffled strains

In this investigation, lactic acid bacteria (LAB) isolated from milk were tested for their antibacterial properties and improved the antimicrobial activity of these isolates using genome shuffling. A total of sixty-one isolates were found in eleven samples, which were then tested using the agar diffusion method for their antibacterial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. Thirty-one strains exhibited antibacterial activity against at least one of the tested pathogens, with an inhibitory zone's diameter varying between 15.0 and 24.0 mm. Two isolates that showed the highest antimicrobial activity were identified as Lactobacillus plantarum CIP 103151 and Lactobacillus plantarum JCM 1149 according to 16S rRNA analysis. In the present study, applying genome shuffling approach significantly enhanced the antibacterial activity of L. plantarum. The initial populations were obtained via ultraviolet irradiation and were treated using the protoplast fusion method. The ideal condition for the production of protoplasts was 15 mg/ml of lysozyme and 10 μg/ml of mutanolysin. After two rounds of fusion, ten recombinants exhibited a significant increase in the inhibition zones versus S. aureus, S. typhimurium, P. aeruginosa, and E. coli, reaching up to 1.34, 1.31, 1.37, and 1.37-fold increase in inhibitory zone respectively. Random Amplified Polymorphic DNA results showed clear differences in DNA banding patterns among the wild strain of L. plantarum CIP 103151 and the three selected shuffled strains using primers 1283 & OPA09. On the other hand, no change was obtained using primers OPD03 neither among the wild strain and the three recombinant strains nor among the three shuffled strains.

Enriching Lactobacilli from Fermented Pulse Dal Flour-Analyzing its Efficacy in Utilizing Carbohydrates and Production of α-galactosidase Enzyme During Pigeon Pea Fermentation

Pigeon peas are an excellent source of carbohydrates, proteins and other nutrients. Many traditional fermented foods are prepared from cereals and combinations of cereals and pulses that usually contain Lactic acid bacteria (LAB), Bacillus, Enterococcus and yeast. Lactobacillus can be used as a starter culture for such fermentation using pulses, as very few reports are available on fermented pulse-based products. Hence, pulse dal flour was used as a source for isolation of Lactobacillus to maintain their functionality, growth characteristics and activity during food processing. In this study, we investigated the potential of lactobacilli from fermented pigeon pea to utilize carbohydrates, the ability to degrade non-digestible oligosaccharides and the production of the α-galactosidase enzyme. Lactobacillus isolated from six different pulse dal flour grew well during fermentation with carbohydrates in mMRS medium. Among Lactobacillus species, only Lactobacillus brevis displayed the highest α-galactosidase activity (1.24 U/ml), where raffinose was added as the sole carbohydrate source in the medium. The isolate was further tested in pigeon pea fermentation, where it showed maximum activity (1.86 U/ml) and complete hydrolysis of non-digestible oligosaccharides was observed. Overall, usage of Lactobacilli could be an excellent opportunity to design and develop a novel pulse-based fermented product contributing to beneficial bioactive compounds and improving the properties of food.

Microbial production of value-added bioproducts and enzymes from molasses, a by-product of sugar industry

Molasses is a major by-product of sugar industry and contains 40-60% (w/w) of sugars. The world's annual yield of molasses reaches 55 million tons. Traditionally, molasses is simply discharged or applied to feed production. Additionally, some low-cost and environmentally friendly bioprocesses have been established for microbial production of value-added bioproducts from molasses. Over the last decade and more, increasing numbers of biofuels, polysaccharides, oligosaccharides, organic acids, and enzymes have been produced from the molasses through microbial conversion that possess an array of important applications in the industries of food, energy, and pharmaceutical. For better application, it is necessary to comprehensively understand the research status of bioconversion of molasses that has not been elaborated in detail so far. In this review, these value-added bioproducts and enzymes obtained through bioconversion of molasses, their potential applications in food and other industries, as well as the future research focus were generalized and discussed.

Isolation and characterization of a new fructophilic Lactobacillus plantarum FPL strain from honeydew

In the present study, a Lactobacillus plantarum FPL strain exhibiting fructophilic behavior has been isolated for the first time from honeydew. It is a probably syntrophic bacterium inhabiting the gastrointestinal tract of Coccus hesperidum L. and taking part in sugar metabolism. The promising growth characteristics and biochemical properties of Lb. plantarum FPL indicate that this may be a facultatively fructophilic species, whose properties are not associated with the loss of the alcohol/acetaldehyde dehydrogenase gene. The article attempts to classify the peculiar behavior of this strain by means of tests that are characteristic for FLAB as well as through a classic identification approach. In this study, we used a reference strain Lb. plantarum NRRL B-4496, which showed no fructophilic properties. With the FLAB group, the new strain shares the habit, such as a fructose-rich environment, the preference of this sugar for growth, and similar growth curves. However, it exceeds FLAB in terms of osmotolerance to high sugar content. The fructophilic Lb. plantarum FPL strain can proliferate and grow on a medium wherein the sugar concentration is 45 and 50% (w/v). Our findings indicate that honeydew can be a promising source of new fructophilic lactic acid bacteria.

Microbial production of mannitol by Lactobacillus brevis 3-A5 from concentrated extract of Jerusalem artichoke tubers

In the present study, the conversion of the extract of Jerusalem artichoke tubers for mannitol production by Lactobacillus brevis 3-A5 was investigated. When the bacterium utilized enzymatic hydrolysates of Jerusalem artichoke extract as the main substrates in batch fermentation, the significant decrease in mannitol productivity was observed when the initial concentration of reducing sugar increased. Then, a strategy of continuous fed-batch fermentation was adopted for improving mannitol production with enzymatic hydrolysates of Jerusalem artichoke extract as main substrates. Although the concentration of mannitol could reach 199.86 g/L at the end of the fermentation, the productivity for the overall process of the fermentation was only 1.67 g/L/H. To improve the mannitol productivity with both higher yield and concentration, the simultaneous enzymatic saccharification and fermentation (SSF) was studied. In SSF, the mannitol production reached 176.50 g/L in 28 H with a productivity of 6.30 g/L/H and a yield of 0.68 g/g total sugar. Our study provides a cost-effective and eco-friendly method for mannitol production from a cheap biomass.