Leuconostoc dextranicum mesenteroides

An extreme example of slime production is found in Leuconostoc dextranicum and L. mesenteroides where so much carbohydrate, called dextran, may be produced that the whole medium in which these cells are growing becomes almost gel-like. This phenomenon has caused pipe blockage in sugar refineries and is deliberately encouraged for the production of dextran as a blood substitute (Chapter 25). 

Dextran Lactobacillus hilgardii, Leuconostoc mesenteroides, Leuconostoc dextranicum. Streptococcus mutans Branched homopolysaccharide of glucose (1 6 a) linkage with side chains a-(1,3)- a-(1,4)-or a-(1,2)-[a-D-Glc-(1 — 6)-a-D-Glc-]n 1W1 3)] [d-GIc(1 — 6)-a-D-Glc-]m The exact structure of each type of dextran depends on the microbial strain... 

Acetobacter capsulatum. Streptococcus bovis . Strep. viridanS, Strep, viscosum, Levconostoc mesenteroideS, Leuconostoc dextranicum, Betabacterium vermiforme, Betacoccus arabinosaceouS, Streptobacterium dextranicum. ... 

Dextrans Glucose Lactobacillus brevis Lactobacteriacaeace dextranicum Leuconostoc mesenteroides... 

Todorov, S. D., Dicks, L. M. T. (2004). Characterization of mesentericin ST99, a bacteriocin produced by Leuconostoc mesenteroides subsp. dextranicum ST99 isolated from boza. Journal of Industrial Microbiology Biotechnology, 31, 323-329. 

Some species of the LAB group such as Leuconostoc mesenteroides subsp. cremoris, Leuconostoc mesenteroides subsp. dextranicum, and Lactococcus lactis subsp. lactis biovar diacetylactis, are known for their capability to produce diacetyl (2,3-butanedione) from citrate, and this metabolism appears especially relevant in the field of dairy products (Figure 13.4). Actually, selected strains belonging to the above species are currently added as starter cultures to those products, e.g., butter, in which diacetyl imparts the distinctive and peculiar aroma. Nevertheless, in particular conditions where there is a pyruvate surplus in the medium (e.g., in the presence of an alternative source of pyruvate than the fermented carbohydrate, such as citrate in milk or in the presence of an alternative electron acceptor available for NAD+ regeneration) (Axelsson, 2(X)9, pp. 1-72), even other LAB such as lactobacilli and pediococci can produce diacetyl by the scanted pyruvate (Figure 13.5). Thus, in addition to butter and dairy products, diacetyl can be present in other fermented foods and feeds, such as wine and ensilage (Jay, 1982). 

Both and H n.m.r. measurements on a bacterial dextran and its acetylated derivative and on a synthetic tri-O-benzyldextran have revealed the main features of their linear a-(l - 6)-linked structures. Bacterial dextrans from Streptococcus viridans B-1351, Streptobacterium dextranicum B-1254, and four strains of Leuconostoc mesenteroides have been subjected to methylation analysis.They differed with respect to the ease of methylation and subsequent hydrolysis of the methylated polysaccharides, owing to significant differences in the frequency and type of chain-branching. An enzymic approach has been used to obtain information on the frequency and distribution of chain-branching in dextrans. Thus, B-512 native dextran was treated with an endo-dextranase (from Pseudomonas UQM 733) and the products were examined by quantitative t.l.c. The relative amount of each oligosaccharide (i.e. linear isomalto-oligosaccharides of DP 2-5... 

Leuconostoc mesenteroides, Streptobacterium dextranicum, Streptococcus mutans and some other bacteria produce extracellular dextran from saccharose with the help of a-l,6-glucan D-fruc-tose-2-glucosyl transferase (dextran sucrase, EC 2.4.1.5). 

The extracellular polysaccharide dextran is produced by the bacteria Leuconostoc mesenteroides, Streptohacterium dextranicum, Streptococcus mutans and some other bacteria. A dextran molecule consists of about 95% of a-(1 6) linked D-glucose units. The remainder are D-glucose molecules linked by a-(1 3) bonds that form side chains (4-182). Some dextrans contain side chains in which D-glucose molecules are also partly bound by a-(1 4) and a-(l—>2) bonds. The type and number of these glycosidic bonds depends on the origin of the dextran. The relative molecular weight of dextran is usually 60-90 kDa. 

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