Leuconostoc lactis

Cogan, T. M., O Dowd, M. and Mellerick, D. 1981. Effect of pH and sugar on acetoin production from citrate by Leuconostoc lactis. AppL Environ. Microbiol. 41, 1-8. 

Mellerick, D. and Cogan, T. M. 1981. Induction of some enzymes of citrate metabolism in Leuconostoc lactis and other heterofermentative lactic acid bacteria. J. Dairy Res. 48, 497-502. 

Ohara, H., Owaki, M., and Sonomoto, K. 2006. Xylooligosaccharide fermentation with Leuconostoc lactis. J. Biosci. Bioeng., 101, 415-420. 

Several studies have reported on the isolation and identification of LAB and yeasts in boza however, to our knowledge, only the studies of Botes et al. (2006), Todorov and Dicks (2006) and Todorov (2010) used biomolecular approaches to identify these microorganisms. In these studies, the numbers of LAB isolated from three boza samples ranged from 9 x 10 to 5 x lO CFU/ml. Carbohydrate fermentation reactions and PCR with species-specific primers classified the isolates as Lactobacillus paracasei subsp. paracasei, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus rhamnosus, Lactobacillus fermentum, Leuconostoc lactis and Enterococcus faecium. 

Palomba, S., Cavella, S., Torrieri, E., et al. (2012) Polyphasic screening, homopolysaccharide composition, and viscoelastic behavior of wheat sourdough from a Leuconostoc lactis and Lactobacillus curvatus exopolysaccharide-produdng starter culture. Appl Environ Microbiol 78, 2737-2747. 

Members of three genera are used as cheese starters. For cheeses that are cooked to a temperature below about 39°C, species of Lactococcus, usually Lc. lactis ssp. cremoris, are used, i.e. for Cheddar, Dutch, Blue, surface mould and surface-smear families. For high-cooked varieties, a thermophilic Lactobacillus culture is used, either alone (e.g. Parmesan) or with Streptococcus salivarius ssp. thermophilus (e.g. most Swiss varieties and Mozzarella). Leuconostoc spp. are included in the starter for some cheese varieties, e.g. Dutch types the function is to produce diacetyl and C02 from citrate rather than acid production. 

Folkjolk Lactococcus lactis subsp. lactis biovar. diacetylactis Leuconostoc meserueroides subsp. cremoris... 

Figure 10.31 Citrate metabolism by Lactococcus lactis ssp. lactis biovar. diacetylactis or Leuconostoc spp. (from Cogan and Hill, 1993).

Although citric acid is present in milk in small amounts (0.07-0.4%), it is a required substrate for production of desirable butter-like flavor and aroma compounds in cultured products. Because seasonal variation in the citrate content of milk is sufficient to affect the flavor of cultured products (Mitchell, 1979), milk may need to be supplemented with citrate to produce cultured products with consistent flavor. Citric acid is metabolized by many organisms found in milk, including S. lactis subsp. diacetylactis, Leuconostoc spp., Bacillus subtilis, various lactobacilli, various yeasts, coliforms, and other enteric bacteria. 

Figure 13.8 Pathway for metabolism of citrate by Leuconostoc spp. and S. lactis subsp. diacetylactis. (1) Citrate permease, (2) citrate lyase, (3) oxaloacetic acid decarboxylase, (4) pyruvate decarboxylase, (5) a-acetolactate synthetase, (6) a-acetolactate carboxylase, (7) diacetyl synthetase, (8) diacetyl reductase, and (9) acetoin reductase.

Starter Distillate occurs as a clear, yellow, water-soluble liquid. It is the steam distillate of a culture of one or more species of Lactococcus lactis subsp. diacetylactis and/or Leuconostoc cremoris grown in a medium of skimmed milk that has been... 

Properties Steam distillate of culture of Streptococcus lactis S. cremoris, S. lactis subsp. diacetylactis, Leuconostoc citrovorum, and L. dextranicum. 

The so-called starter distillates used by the dairy industry are now produced on a commercial scale from lactic acid cultures. These distillates in which 70% of the substrate is converted to diacetyl have been patented(67) and are used to impart a buttery taste to edible oils. They are manufactured by the steam distillation of cultures of bacteria grown on a medium of skim milk fortified with 0.1% citric acid. Organisms used are Streptococcus lactis. S. cremoris. S. lactis subsp. diacetvlactis. Leuconostoc citrovorum and L dextranicum. Diacetyl comprises 80-90% of the flavor compounds in the aqueous distillate but is present at only 10-100 ppm. 

Cheese Lactococcus lactis subsp. lactis Lactococcus lactis subsp. lactis var. diacetylactis Lactococcus lactis subsp. cremoris Leuconostoc mesenteroides subsp. cremoris Lactobacillus delbrueckii subsp. lactis Lactobacillus helveticus Lactobacillus easel Lactobacillus delbrueckii subsp. bulgaricus Streptococcus thermophilus Propionibacterium freudenreichii... 

Huorescently labeled ohgonucleotide probes were developed to detect Lact. lactis. Lb. plantarum, and Leuconostoc mesenteroides in Stilton cheese by Ercolini et al. (2003). A combination of these probes allowed the assessment of the spatial distribution of the different microbial species in the dairy matrix, with impUcations of significance in understanding the ecology of Stilton matrix. 

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). 

Lactobacillus and Propionibacterium strains were evaluated by El-Nezami et al. (2002) regarding their ability to remove seven Fusarium toxins (trichothecenes) from solution. Results showed that L. rhamnosus GG and Propionibacterium freudenrei-chii spp. shermanii JS were able to bind 18-93% of the deoxynivalenol, diacetoxy-scirpenol, and fusarenon in solution, while L. rhamnosus LC-705 removed 10-64% of deoxynivalenol and diacetoxyscirpenol from liquid medium. When comparing the ability of lactic and propionic bacteria to remove toxin from solution, Niderkom, Boudra, and Morgavi (2006) found that deoxynivalenol and fumonisin removal was strain specific, and that in general propionic acid bacteria was less efficient than lactic acid bacteria. The best results were achieved with L. rhamnosus for ranoval of deoxynivalenol (55%), Leuconostoc mesenteroides for fumonisin Bi (about 82%), and L. lactis for fumonisin B2 (100%) (Niderkom et al., 2006). 

For utilization of hemicellulose, utilization of pentose sugars such as xylose and arabinose is a major problem. Some LAB such as Lactobacillus pentosus (Bustos et al., 2(X)5), Lactobacillus brevis (Chaillou et al., 1998), Lb. plantarum (Helanto et al., 2007), and Leuconostoc (Leuc.) lactis (Ohara et al., 2006) are known to ferment either or both arabinose and xylose. The metabolic pathway of pentose is... 

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