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

Abstract

Aims:The studies of the production of exopolysaccharides by lactose-negative yeast and a yogurt starter cocultivated in a natural substrate containing lactose may be considered of interest because they reveal the possibilities for high-efficiency synthesis of biopolymers by mixed cultivation. Methods and Results: The mixed culture Rhodotorula rubra GED10 + (Streptococcus thermophilus 13a + Lactobacillus bulgaricus 2-11) was cultivated in cheese whey ultrafiltrate (WU) (44AE0 g lactose l )1 ) at initial pH 6AE0, 28°C, under intensive aeration (air-flow rate 1AE0 l l )1 min )1 , agitation 220 rev min )1 ) in a MBR AG fermentor. The mixed culture manifested the highest activity for synthesis of exopolysaccharides (19AE3 g l )1 ) and cell mass (21AE0 g l )1 ) at the 84th hour. The yogurt starter synthesized neutral exopolysaccharides, while the mixed culture yeast + yogurt starter produced acidic exopolysaccharides containing uronic acid (6%). The neutral sugar composition was identified as mannose, glucose, galactose, xylose and arabinose. Mannose dominated in the polymer composition (83%) that was produced only by the yeast (97%). Conclusions: Lactose in the WU can be effectively utilized by a co-culture of lactose-negative yeast-yogurt starter for synthesis of exopolysaccharides. Significance and Impact of the Study: The present findings propose an alternative use of WU as a costeffective carbohydrate substrate, and suggest that the lactose-negative yeast Rhodotorula rubra can have industrial application as producers of exopolysaccharides.

Removal of Zn(II) from electroplating effluent using yeast biofilm formed on gravels: batch and column studies

“…Therefore, the present results indicated that glucose, mannose and glucuronic acids were the most abundant sugars in EPS produced by C. rugosa and C. laurentii. Similar work was reported in case of yeasts belonging to Candida, Cryptococcus, Rhodotorula and Sporobolomyces genera which produced EPS such as mannan, glucomannan and glucan [26,28-30]. Since the EPS produced by yeast are more easily separated from the culture broth than those produced by bacteria; they are more attractive for a large scale production [31].…”

“…The carbohydrate composition of EPS was also determined using HPLC (chromatograph Waters, Milford, MA, USA) following the method of Simova et al [26]. The dialysed EPS was characterized through infrared analysis using FT-IR spectrophotometer (Perkin Elmer Spectrum 1).…”

Activation and immobilization of phenol-degrading bacteria on oil palm residues for enhancing phenols degradation in treated palm oil mill effluent

“…However, the highest rate of EPS production was obtained when two strains were mixed together obtaining a maximum 85% yield of EPS after 6 days incubation. In accord with earlier findings, the mixed culture of S. thermophilus 13a and L. bulgaricus exhibited higher EPS synthe- sizing activity compared to the single strain due to a mutual stimulation of cell metabolism [36]. The bacterial EPS is essential for biofilm formation, aggregating and sheathing the cells as well as protecting them against adverse conditions [37].…”

Characterization and Safety Evaluation of Exopolysaccharide Produced by Rhodotorula minuta BIOTECH 2178

“…In coping with the growing demand for quality food products, the functionality of polysaccharide is now one of the widely explored food ingredients because of its many prospective applications. Recently, there is a growing interest in the isolation of microbial exopolysaccharide [1], [2]. This compound has been found to have multifarious application in the industry because of its wide diversity in structural and chemical properties.…”