Optimization of ethanol production using pretreated corn cob and sugarcane bagasse hydrolysate by Candida parapsilosis strain BKR1

Abstract

Aim: Bioethanol is a suitable and best alternative to the replenishing fossil fuel in the fast growing world. To meet the rising demand of ethanol in the global market, there needs to be lot of improvisation in the existing process. One such method is to utilize more pentose sugar along with hexose in the substrate for better yield. In the present study, the efficiency of Candida parapsilosis BKR1 species for the production of ethanol was studied in corncobs and sugarcane bagasse. Methodology: The sugarcane bagasse and corn cobs were collected from local market, Coimbatore and Candida parapsilosis BKR1 was isolated from sugar cane extract. The lignocellulosic materials were treated by various combination of pretreatment (acid and alkali pretreatment) and hydrolysis (acid, alkaline and sodium carbonate hydrolysis) methods to maximize the fermentable sugars in the substrate. The fermentation conditions such as pH, inoculum age, nitrogen source and fermentation time for ethanol production were optimized and the fermented media of both substrates were subjected to distillation to find ethanol percentage by gas chromatography. Results : Acid pretreatment with sodium carbonate hydrolysis produced higher sugar yield for both the lignocellulosic materials. The studies on optimization showed maximum production using 24th hr inoculum, with 1% nitrogen source at pH 6, during 6th day of fermentation @ 120 rpm for corn cobs and sugarcane bagasse. The results revealed that ethanol concentration in sugarcane bagasse and corn cobs were 27.93 g l-1 and 20.78g l-1, respectively. Interpretation : The Candida parapsilosis BKR1 strain efficiently utilized sugarcane bagasse than corn cobs and produced high concentration ofethanol.