Lactic acid bacteria applications

In more recent times chemically defined basal media have been elaborated, on which the growth of various lactic acid bacteria is luxuriant and acid production is near-optimal. The proportions of the nutrients in the basal media have been determined which induce maximum sensitivity of the organisms for the test substance and minimize the stimulatory or inhibitory action of other nutrilites introduced with the test sample. Assay conditions have been provided which permit the attainment of satisfactory precision and accuracy in the determination of amino acids. Experimental techniques have been provided which facilitate the microbiological determination of amino acids. On the whole, microbiological procedures now available for the determination of all the amino acids except hydroxy-proline are convenient, reasonably accurate, and applicable to the assay of purified proteins, food, blood, urine, plant products, and other types of biological materials. On the other hand, it is improbable that any microbiological procedure approaches perfection and it is to be expected that old methods will be improved and new ones proposed by the many investigators interested in this problem. 

Vescovo, M., Torriani, S., Orsi, C., Macchiarolo, F. and Scolari, G. (1996) Application of antimicrobial-producing lactic acid bacteria to control pathogens in ready-to-use vegetables . Journal of Applied Bacteriology, 81, 113-119. 

De Vuyst L and Leroy F. 2007. Bacteriocins from lactic acid bacteria production, purification, and food applications. J Mol Microbiol Biotechnol 13 194-199. 

The key feature which draws attention to these peptides in respect to food applications is their ability to inhibit undesirable organisms, either spoilage or pathogenic organisms. Although the peptides from eukaryotic sources appear far-removed from immediate application in foods, it is important to study their mechanism(s) of action in relation to those of lactic acid bacteria to better understand commonalities in structure-function Such commonalities may serve as a base from which to initiate molecular... 

Lactose is readily fermented by lactic acid bacteria, especially Lactococcus spp. and Lactobacillus spp., to lactic acid, and by some species of yeast, e.g. Kluyveromyces spp., to ethanol (Figure 2.27). Lactic acid may be used as a food acidulant, as a component in the manufacture of plastics, or converted to ammonium lactate as a source of nitrogen for animal nutrition. It can be converted to propionic acid, which has many food applications, by Propionibacterium spp. Potable ethanol is being produced commercially from lactose in whey or UF permeate. The ethanol may also be used for industrial purposes or as a fuel but is probably not cost-competitive with ethanol produced by fermentation of sucrose or chemically. The ethanol may also be oxidized to acetic acid. The mother liquor remaining from the production of lactic acid or ethanol may be subjected to anaerobic digestion with the production of methane (CH4) for use as a fuel several such plants are in commercial use. 

In recent years several applications of the HC1 proteolysis have been published in the field of Se speciation, for example, as regards Se-enriched lactic acid bacteria [66], mullet and cockles [8], and algae [67], where the technique provided extraction efficiencies of greater than 90 percent and preserved the integrity of the selenoamino acids. The general usefulness of this method of Se speciation is, however, questionable. Sometimes the authors do not state clearly whether phenol - an essential compound for the prevention of oxidation of SeCys - was used or not. In practice, neither phenol nor the short-duration MW-assisted irradiation can prevent the alteration of selenoamino acids [68-71], At the moment, no final conclusion on the applicability of HC1 proteolysis can be drawn, as CRMs certified for SeCys are still unavailable. On the other hand, an Se extraction efficiency of 80-90 percent can be achieved with this method only if either proteins are at least partly separated from the other components of the matrix, for example, separate analysis of fish muscles is carried out [8], or a considerable portion of Se is originally contained in inorganic forms in the sample, as observed by B Hymer and Caruso [1] in the case of Se-enriched food supplements. 

The approach of Casiot et al. [21] was soon accepted and followed in the held of Se speciation. Wrobel et al. [91] applied a bacterium (Arthrobacter luteus) derived lysing enzyme mixture added with PMSF to study the intermediary molecules of Se metabolism of Se-enriched yeast without proteolysis. In order to tailor the cell wall degrading mechanism to the samples under test, Michalke et al. [77] used bacterial lisozyme and pronase E, either alone or in combination, for the Se speciation of Se-enriched lactic acid bacteria. Independent and simultaneous experiments were carried out with the two enzymes, thus achieving outstanding total Se-extraction efficiency (85-105 percent) with the sole application of pronase E and relatively low chromatographic recovery (8-12 percent) (still... 

Biobased polymers from renewable materials have received increased attention recently. Lactate is a building block for bio-based polymers. In the United States, production of lactic acid is greater than 50,000 metric tons/yr and projected to increase exponentially to replace petroleum-based polymers. Domestic lactate is currently manufactured from corn starch using the filamentous fungus Rhizopus oryzae and selected species of lactic acid bacteria. The produced lactic acid can then be polymerized into polylactic acid (PLA) which has many applications (Hatti-Kaul et al., 2007). However, so far, no facility is built to use biomass derived sugars for lactic acid production. More research needs to be done to develop microbes using biomass derived sugars for lactate production. 

McKay, L.L. and Baldwin, K.A. 1990. Applications for biotechnology Present and future improvements in lactic acid bacteria. FEMS Microbiology Reviews 87 3-14. 

Noteworthy results have been attained also with our strain collection of lactic acid bacteria, of lignocellulose-degrading microbes, and their technological application. 

Most polysaccharides used today are of plant origin. However, also bacteria produce polysaccharides. Especially extracellular polysaccharides (eps s) produced by lactic acid bacteria may find application in foods. Lactic acid bacteria are food-grade organisms and the eps s produced offer a wide variety of structures. The presence of eps is considered to contribute greatly to texture and structure of fermented milk products. An exopolysaccharide produced by Lactococcus lactis ssp. cremoris B40 was chosen as a subject of study. The eps was a gift from the Dutch Institute of Dairy Research (NIZO), Ede, the Netherlands. The eps had no gelling properties, could not be precipitated in plates by ethanol or cetylpyridinium chloride and did not show interaction with Congo red. 

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