Hydrolysis of cassava starch by co-immobilized multi-microorganisms of Loog-Pang (Thai rice cake starter) for ethanol fermentation.

Loog-Pang (Thai rice cake starter) is an effective and inexpensive microbial source for the hydrolysis of cassava starch to glucose. A process for hydrolysis of cassava starch to glucose by Loog- Pang was improved by co-immobilized multi-microorganisms (IC) using thin shell silk cocoon (TSC). After incubation at 35°C for 120 h, the IC-TSC system converted 20% w/v cassava starch slurry into clear glucose syrup containing a glucose concentration of 145.5 g/L (composed of 98.8% glucose and 1.2% oligosaccharides), with little or no contamination by microorganisms. The glucose concentration from the starch hydrolysis process using the IC-TSC system was approximately 1.3 times more than that of suspended cultures (SC). The starch hydrolysate could be used as the carbon source for ethanol fermentation without sterilization. A concentration of ethanol of 71.2 g/L (9.1%, v/v) was obtained at 36 h fermentation of the starch hydrolysate by Saccharomyces cerevisiae M30.