ETHANOL PRODUCTION FROM SORGHUM STRAW WITH ACID PRETREATMENT USING Saccharomyces cerevisiae

Abstract

Fermentation is a metabolic process of microorganisms to obtain energy by breaking down organic compound. Sorghum straw was fermented with different concentration substrate (15gm, 30gm , 45g and 60gm) with 0.5% ,1% yeast in different fermentation period (4th day, 8th day, 12th and 16th days) with the aim of ethanol production from Sorghum straw. Among the different substrate concentration 15 gram of substrate mixed with 1% yeast produced high quantity of ethanol on 4th day of fermentation. After the acid pre-treatment and addition of high amount of inoculum concentration (1% yeast ), ethanol production was increased as compared with untreated 15 gram substrate mixing with 1% inoculum concentration. The maximum ethanol production for 15g untreated substrate was 0.04%, where as that of acidpretreated was 0.15%. The reducing sugars contents increased through process as the fermentation period increased. Moreover, on 12th day of fermentation period, the highest reducing sugar concentration (1.36mg/ml) was gained from acid pretreated 30gram Sorghum straw substrate mixed with 1% inoculums concentration, whereas the same substrate concentration showed 1.33mg/ml in untreated substrate. The cell density was higher in acid pre-treated substrate combine with 1 % inoculum (yeast) concentration (2.46mg/ml) than untreated ones (2.30mg/ml). The maximum ethanol production was observed on 4th day of fermentation in acid pre-treated substrate and high inoculums concentration (1% yeast). After 4th day of fermentation period, the rate of ethanol production decreased in treated and untreated substrate. The study revealed that it is possible to produce bio-ethanol from Sorghum straw. Therefore, it is recommended to conduct experimental studies to increase ethanol yield