Synthesis of Mannose-Rich Exopolysaccharide by Rhodotorula glutinis 16P Co-Cultured with Yeast or Bacteria

Abstract

Rhodotorula glutinis, Kluyveromyces lactis, Lactobacillus helveticus, ExopolysaccharidesExopolysaccharides from the lactose-negative yeast Rhodotorula glutinis 16P were synthe sized by co-cultivation with the yeast Kluyveromyces lactis MP11 or with the homofermentative lactic acid bacteria Lactobacillus helveticus 9A in a cheese whey ultrafiltrate. Exopoly saccharides were produced by lactose hydrolysis, performed by two pathways: with ß-galactosidase from Kluyveromyces lactis MP11 which assimilates glucose and galactose; with ß-galactosidase and Lactobacillus helveticus 9A which uses lactic acid. By growing the two mixed cultures maximum yield was obtained as follows: 11.4 g/1 and 15.8 g/1, respectively. Structural units of the carbohydrate composition of the two polymers are mannose ( 7 2 .4 -6 3 .5 % ), glucose (2 .0 -1 5 .9 % ), galactose (2 5 .3 -1 9 .8 % ) and xylose ( 3 .6 -4 .3 % ) . Mannose dominated in the polysaccharide compositions.

Exopolysaccharides produced by mixed culture of yeast Rhodotorula rubra GED10 and yogurt bacteria (Streptococcus thermophilus 13a + Lactobacillus bulgaricus 2-11)

“…The yogurt culture produced insignificant amounts of mannose ( ca 3% by S. thermophilus 13a + L. bulgaricus 2‐11). Mannose contents in the exopolysaccharides synthesized by the mixed culture R. rubra GED10 + ( S. thermophilus 13a + L. bulgaricus 2‐11) are higher than the reported data for R. rubra grown in a glucose medium (Adami and Cavazzoni 1990) and for the mixed cultures of R. glutinis 16P with K. lactis MP11 or with L. helveticus 9A (Simova et al. 2000).…”

“…1995). The mixed culture R. rubra GED10 + ( S.thermophilus 13a + L. bulgaricus 2‐11) manifested higher exopolysaccharide production level than that of the mixed cultures R. glutinis 16P + Kluyveromyces lactis MP11 and R. glutinis 16P + L. helveticus 9A in previous studies – ca 1·5 times higher (Simova et al. 2000), 2·3 times higher activity than the monoculture R. rubra GED10 grown in a glucose synthetic medium, and 1·8 times higher activity than the monoculture R. rubra grown in a glucose synthetic medium (Adami and Cavazzoni 1990).…”

“…Notwithstanding the fact that authors’ results differ significantly in terms of carbohydrate composition and monosaccharides ratio in the biopolymers (depending on the growth conditions and the specific properties of the strain producer), a number of authors showed the prevailing presence of mannose in exopolysaccharides produced by Rhodotorula (Elinov et al. 1988; Adami and Cavazzoni 1990; Simova et al. 2000; Cho et al.…”

“…The carbohydrate composition in the polysaccharides was determined after hydrolysis with 2 n H 2 SO 4 for 8·0 h at 105°C. Determination of neutral sugars in the hydrolysate (by gas chromatography) were described earlier (Simova et al. 2000).…”

“…Substrates containing lactose used for high‐efficiency synthesis of exopolysaccharides by lactose‐negative yeast are of certain interest. The synthesis can occur in associated cultivation of the yeast strain producers and lactose‐transforming micro‐organisms (Simova et al. 2000).…”