Oligosaccharides in straw hydrolysate could improve the production of single cell protein by Saccharomyces cerevisiae.

BACKGROUND Using agricultural wastes to produce single cell protein (SCP) can effectively reduce production costs. The aims of this study were to investigate the effects of enzyme loading on the components of the hydrolysate of rice straw (RS) and their effects on the growth of yeast. RESULTS At the same glucose concentration, the dry weight of cells produced in the hydrolysate was 2.89 times higher than that in 2 g/L yeast extract (YE) medium, indicating that the hydrolysate was a suitable substrate for yeast growth. Ethanol precipitation followed by analysis showed that there were many oligosaccharides in the hydrolysate. The amount of cellulase had an important effect on the production of monosaccharides, but had a lesser effect on the amounts and compositions of oligosaccharides. Adding oligosaccharides to the medium had no effect on ethanol production, but it effectively promoted yeast growth and increased SCP production. The results indicate that oligosaccharides was an important growth factor for yeast growth in the hydrolysate. Compared with YE medium, the cost of the medium with the hydrolysate was reduced by 68.47% when the same dry cell weight was obtained. CONCLUSION Oligosaccharides in the hydrolysate can improve SCP production with low nutrient cost. This finding could reduce the amounts of cellulase required during saccharification and nutrients during culture, providing a new low-cost method for SCP production. This article is protected by copyright. All rights reserved.