Direct Bioconversion of Cellobiose into Ethanol Using Co-Immobilized Cells of Lipomyces starkeyi and Saccharomyces cerevisiae by Fed-batch System

Abstract

Cellobiose as intermediate and glucose is end product of cellulose hydrolysis, respectively are known as inhibitor to the enzyme reaction; therefore continuous removal of these products by direct conversion to ethanol, is though advantages. These paper reported development of a co-immobilization cell system In calcium alginate between Lipomyces starkey! as source of periplasinic 3-glucosidase and Saccharomyces cerevisiae to convert cellobiose directly into ethanol at high efficiency in repented fed-bitch reactor. The compensate temperature and pH of the co-immobi lized cell for the conversion of cellobiose were found to be 30'C and 4.4; respectively. In the repeated batch, 50 g/l cellobiose has been metabolized into ethanol in IS hour; and the co-immobilized cells preparation showed an operational stability of more than 24 of repeated batches for 400 hour. The ethanol yield based on substrate were 0.4- 0.46 g ethanollg ceilobiose 80-86% yield. In the repeated fed-batch, 6-7% of ethanol was produced utilizing 15% cellobiose in 50-75 hour. The complete conversion 0.51 prolonged into 96-120 hour. g ethanol/g cellobiose was obtained when the reaction was prolonged into 96-120 hour.