Lactic acid-forming bacteria Lactobacillus

Alternatives to using ruminant foods to provide CLA in the diet are of great interest to the food-processing industry, perhaps most so in dairy processing. Sieber et al (2004) reviewed the impact of microbial cultures on CLA in dairy products. Several strains of Lactobacillus, Propionibacterium, Bifidobacterium, and Enterococcus are able to form CLA from linoleic acid lactic acid bacteria and propionibacteria appear to show promise to increase CLA during ripening of cheese. Presently, data are not convincing that this... 

Dextran is synthesized from sucrose by certain lactic acid bacteria, the best-known being Leuconostoc mesenteroides and Streptococcus mutans. Dextran is also formed by the probiotic Lactobacillus brevis to create the crystals of tibicos or water kefir-fermented beverage with reported health benefits. 

Racemic DL-lactic acid can be synthesized by fermentation using appropriate bacteria Lactobacillus helvetics in Table 1.1), but it is more easily synthesized by following the chemical process shown in Scheme 1.3. Here, the DL-lactic acid is produced by hydrolysis of lactonitrile that is generally formed by the addition reaction of acetaldehyde and hydrogen cyanide. Industrially, the lactonitrile is obtained as a by-product of acrylonitrile production (Sohio process).The lactic acid thus prepared is purified by distillation of its ester as described above. 

Bacteriocins are defined as proteinaceous substances having an antimicrobial effect against closely related species. Strains among Lactobacillus and Pediococcus spp. form bacteriocins that are effective against Staphylococcus aureus and Listeria monocytogenes. Both are regarded as potential health risks in meat products. A recent review article by Stiles and Hastings (1991) covers the subject on the potential use of lactic acid bacteria in meat preservation. 

Lactate. Hard rennet cheeses represent a selective habitat for propionic acid bacteria, since they contain lactate formed as the end product of lactose fermentation by lactic acid bacteria. Unlike many other bacteria, propioni-bacteria can utilize lactate efficiently, which is the reason why propioni-bacteria are so abundant in hard, ripened cheeses. Propionic acid bacteria use lactate best in the presence of yeast extract (Antila, 1954), but even higher stimulatory effect is exerted by cell-free extracts of lactic acid bacteria. Streptococcus thermophilus and Lactobacillus spp. (Hietaranta and Antila, 1953). Lactate as a carbon source supports higher growth rates of propionic acid bacteria than lactose (El-Hagarawy et al., 1954). 

The lactic acid bacteria of grape must and wine belong to the genera Lactobacillus, Leuconostoc, Oenococcus and Pediococcus. Besides their morphology in coccal or rod-like forms, the homofer-mentative or heterofermentative character is a deciding factor in their classification. Homofer-mentative bacteria produce more than 85% lactic acid from glucose. Heterofermentative bacteria produce carbon dioxide, ethanol and acetic acid in addition to lactic acid. 

Many examples have been reported on the biosurfactants potential as anti-adhesive coatings. The amount of biofilm formed by Salmonella typhimurium. Salmonella enterica, Escherichia coli and Proteus mirabilis in vinyl urethral catheters coated with surfactin was reduced as compared to the uncoated controls [124], Also, biosurfactants from probiotic lactobacilli successfully prevented the adhesion of uropatho-gens, and subsequent urogenital infections [19-21, 125], Biosurfactants from lactic acid bacteria (Streptococcus ther-mophilus A and Lactococcus lactis 53) were effectively used to avoid microbial colonization of silicone rubber voice prosthe-ses, thus their premature failure [26,27]. These bacterial [22] and Lactobacillus paracasei [126] biosurfactants were found to possess antimicrobial and anti-adhesive activity against... 

---