Diversity of Heteropolysaccharide-Producing Lactic Acid Bacterium Strains and Their Biopolymers

Abstract

Thirty-one lactic acid bacterial strains from different species were evaluated for exopolysaccharide (EPS) production in milk. Thermophilic strains produced more EPS than mesophilic ones, but EPS yields were generally low. Ropiness or capsular polysaccharide formation was strain dependent. Six strains produced high-molecular-mass EPS. Polymers were classified into nine groups on the basis of their monomer composition. EPS from Enterococcus strains were isolated and characterized.Certain lactic acid bacteria (LAB) produce exopolysaccharides (EPS), either capsular polysaccharides (CPS) that are tightly associated with the cell surface or slime EPS that are secreted into the extracellular environment. EPS from LAB can be divided into homopolysaccharides, which are polymers composed of one type of monosaccharide, and heteropolysaccharides (HePS), which are polymers of repeating units that are composed of two or more types of monosaccharides (5,6,7,11). A large biodiversity of HePS from LAB exists regarding their composition and structure, molecular mass (MM), yield, and functionalities (5,7,35). Further, polymer formation is strongly influenced by culture conditions (1,7,22,32). Recently, the molecular genetics of HePS biosynthesis have been studied for different LAB species (6, 25). Several glycosyltransferases involved in the assemblage of the HePS repeating units have been discovered (17,18,35). EPS can act as viscosifying, stabilizing, gel-forming, and/or water-binding agents in various foods (6, 10). Additionally, they have been claimed to display properties beneficial to health (6, 29). Little attention has been paid to CPS formation by food grade LAB. Exploration of the biodiversity of wild LAB strains is the most suitable approach to search for a desired EPS phenotype (28,33,34). The aims of this study were to seek new EPS-producing LAB strains, to characterize their biopolymers, and to explore their diversity to find novel or interesting HePS or HePS-producing strains.EPS screening, isolation, and characterization. Two hundred one thermophilic (11 strains of Lactobacillus acidophilus, 79 of Lactobacillus delbrueckii subsp. bulgaricus, 1 of L. delbrueckii subsp. lactis, 1 of Streptococcus macedonicus, and 42 of Streptococcus thermophilus) and mesophilic (23 strains of Enterococcus faecalis, 1 of Enterococcus faecium, 5 of Lactobacillus casei, 29 of Lactobacillus paracasei, and 9 of Lactobacillus rhamnosus) LAB strains (CERELA Culture Collection, Tucumán, Argentina) were used throughout this study. All bacteria were stored as previously described (22). Before experimental use, cultures were propagated twice in MRS (Britania, Buenos Aires, Argentina) for lactobacilli or in LAPTg (27) for streptococci and enterococci.Screening for EPS-producing LAB was performed with reconstituted skim milk (10%, wt/vol) at 37°C for 16 h using cultures propagated in milk as the inoculum (1%, vol/vol). Noninoculated medium was used as a control. Cell counts, expressed as numbers of CFU per milliliter, were determined by pour pla...

Exopolysaccharides producing Lactobacillus fermentum strain for enhancing rheological and sensory attributes of low-fat dahi

“…bulgaricus NCDC 285 were glucose: rhamnose : galactose in a proportion of 1 : 13 : 1.5 and rhamnose : galactose in a proportion of 1:6.8 respectively ( Table 1). The monosaccharides most frequently occurring in the various LAB strains are glucose (Cerning 1995), rhamnose (Mozzi et al 2006;Nakajima et al 1990) and galactose (De Vuyst et al 2003;Doleyres et al 2005).…”

Exopolysaccharide and lactic acid bacteria: Perception, functionality and prospects

“…Kefiranofaciens, isolated from a fermented food product Kefir in North Caucasus, were able to produce enormous amount of hetero-exopolysaccharides (De Vos et al, 2009;Harutoshi, 2013). A number of microbial species such as Streptococcus thermophilus, Lactococcus lactis, L. delbrueckii, and Lactobacillus helveticus have been well recognized with an ability to produce heteroexopolysaccharides (Mozzi et al, 2006) In addition, lactic acid bacteria of homo-fermentative nature are well known for their ability to produce hetero-EPS, whereas, a hetero-fermentative strain L. fermentum has been found to produce exopolysaccharide with confirmed chemical nature determination (Leo et al, 2007). Although previously presence of inadequate production of hetero-exopolysaccharides has been confirmed in L. brevis and L. buchneri in the growth medium containing glucose or sucrose as carbon sources, no results were reported on the origin (Figueroa et al, 1995 50-350, 80-600, 60-150, 50-60 and about 140 mg/liter of hetero-exopolysaccharide (Tallon et al, 2003;Tsuda and Miyamoto, 2010;Harutoshi, 2013).…”

New Approaches in Gastritis Treatment

“…subsp. bulgaricus, L. helveticus, L. paracasei, L. pentosus, L. plantarum, L., rhamnosus, L. reuteri, L. casei, Leuconostoc mesenteroides and Streptococcus thermophilus although it is a strain-dependent property (Mozzi et. al., 2006;Ruas-Madiedo et.…”

“…(1994) reported anti-ulcer effects of the cell wall polysaccharide of bifidobacteria, lactobacilli and streptococci strains, which were attributed to the high rhamnose content of the polymers (> 60%). Rodríguez et al (2009Rodríguez et al ( , 2010 reported the first evidences on the beneficial effects of both the EPS-producing LAB strains and the biopolymer on gastritis experimental animal models using acetyl salicylic acid ( The strains CRL 1190 and CRL 87 also produced capsular polysaccharide in addition to the slime EPS in milk and was able to form ropy milk cultures similar to CRL 638, while the strain CRL 804 was negative for both the capsular and ropy phenotypes (Mozzi et. al., 2006).…”