Isolation and evaluation of thermophilic bacteria for ethanol fermentation from agricultural materials

Abstract

This study was carried out to select the various strains of thermophilic bacteria having the ethanol fermentation activity. In this study, a total of 27 strains were isolated from different agricultural materials of ripe fruits, sawdust, bagasse from sugarcane, molasses, flowers of fruit-tree and honey. In the fermentation testing, eleven of the strains performed the rapid fermentation rate. In the testing of colony growth after 72 hours of incubation at different temperature levels of 30, 35, 40, 45 and 50^oC, seven bacterial strains (MC3, BM2, BM3, RD, HM1, HM2 and MO) could grow at 50^oC. Five strains (MC3, BM2, HM1, HM2 and MO) gave the possibility of fermentation from 6 testing sugar resources (glucose, sucrose, galactose, lactose, arabinose and xylose); whereas two strains BM3 and RD gave no fermentative signal from arabinose but could ferment from other 5 sugar resources. Based on the characteristics of morphology, physiology, biochemistry and DNA sequencing analyses, the selected bacterial strain (MO) was characterized as Bacillus subtilis.