Carbon Source Requirements for Exopolysaccharide Production by Lactobacillus casei CG11 and Partial Structure Analysis of the Polymer

Abstract

Exopolysaccharide production by LactobaciUlus casei CGll was studied in basal minimum medium containing various carbon sources (galactose, glucose, lactose, sucrose, maltose, melibiose) at concentrations of 2, 5, 10, and 20 g/liter. L. casei CGll produced exopolysaccharides in basal minimum medium containing each of the sugars tested; lactose and galactose were the poorest carbon sources, and glucose was by far the most efficient carbon source. Sugar concentrations had a marked eflect on polymer yield. Plasmid-cured Mucderivatives grew better in the presence of glucose and attained slightly higher populations than the wild-type strain. The values obtained with lactose were considerably lower for both growth and exopolysaccharide yield. The level of specific polymer production per cell obtained with glucose was distinctively lower for Mucderivatives than for the Muc+ strain. The polymer produced by L. casei CGll in the presence of glucose was different from that formed in the presence of lactose. The polysaccharide produced by L. casei CGII in basal minimum medium containing 20 g of glucose per liter had an intrinsic viscosity of 1.13 dl/g. It was rich in glucose (76%), which was present mostly as 2or 3-linked residues along with some 2,3 doubly substituted glucose units, and in rhamnose (21%), which was present as 2-linked or terminal rhamnose; traces of mannose and galactose were also present.

Combined Effects of Temperature and Medium Composition on Exopolysaccharide Production by Lactobacillusrhamnosus RW‐9595M in a Whey Permeate Based Medium

“…In this study two purification procedures were tested for quantifying EPS production in culture broth, a first method conventionally used in the literature (12,14,17) and a second method recently developed in our research group (13). Data from the conventional method showed a much lower EPS recovery compared with those from the UF method ( Figure 1 and Table 1).…”

“…Two procedures for EPS purification were carried out. The first procedure used the conventional method based on chilled ethanol precipitation followed by a trichloroacetic acid precipitation, with intermediate steps of dialysis and lyophilization, previously described by Cerning et al (14). The lyophilized powder was referred to purified EPS.…”

Physicochemical characterisation of the exopolysaccharides of Streptococcus thermophilus ST‐143

“…Tuinier et al (1999b) detected ash (9 mg 100 mg À1 ) and moisture (6 mg 100 mg À1 ) on comparable levels and concluded that such a low amount of impurities did not affect their rheological investigations. Literature data on purity levels of EPS isolates show a broad range from 2-98 mg 100 mg À1 (Cerning et al, 1994;Tuinier et al, 1999b;Doleyres et al, 2005;Goh et al, 2005b); however, the applied calculation modes are not consistent. For example, Goh et al (2005b) reported on an EPS preparation with a purity of 98% but related the carbohydrate content to the dry matter of the EPS isolate.…”

Characterization of extracellular polymers synthesized by tropical intertidal biofilm bacteria

“…After the cultures reached the exponential phase of growth (24-36 h), the culture broths were heated at 100°C for 15 min to inactivate the enzymes capable of degrading the polymer (Cerning et al 1994). The cells were then removed by centrifugation at 4000 g for 30 min at 4°C, and filtered through 0AE47-lm pore diameter HVLP polyvinylidene fluoride (Millipore, Billerica, MA, USA) filters.…”