Development of semi-defined rice straw-based medium for butanol production and its kinetic study.
Rice straw is one of the potential economic feedstock for biobutanol production through ABE fermentation. However, the rice straw hydrolysate-based fermentation medium needs to be supported with nutritional elements. In this study, an attempt is made to optimize the rice straw hydrolysate-based fermentation medium employing Clostridium acetobutylicum MTCC 481 using Taguchi design of experiments (DOE) statistical model. Initially, a set of 12 nutrient components viz. MgNO3·6H2O, FeNO3, NH4NO3, yeast extract, PABA, biotin, PABA + biotin mixture, CaCl2, KCl, NaCl, MgSO4and CH3COONa were screened through classical (one-variable-at-a-time) method. Based on the results, four components (PABA, yeast extract, MgSO4and CH3COONa) were found to have significant impact, and were further subjected to statistical optimization through Taguchi DOE method. These experiments revealed that RSH supported with 3 g L-1of yeast extract and 4 mg L-1PABA to RSH was the most optimum fermentation medium. Experiments using 2 L bioreactor with this optimum fermentation medium showed nearly complete utilization of soluble sugars with the production of 8.7 g L-1of total solvents and 6 g L-1of butanol. The experimental data were fitted to kinetic models reported in the literature to determine the kinetic parameters of the fermentation process. An interesting result was revealed from this analysis that the under optimized fermentation medium, the kinetic parameters for both shake flask and bioreactor level were similar. This essentially means that effect of scale of operation is rendered insignificant when fermentation medium is under optimum conditions.
Centre for Energy, Indian Institute of Technology Guwahati, Guwahati, 781 039, Assam, India.
Amrita
A
Ranjan
Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781 039, Assam, India.
Rahul
R
Mayank
Centre for Energy, Indian Institute of Technology Guwahati, Guwahati, 781 039, Assam, India. vmoholkar@iitg.ernet.in.|Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781 039, Assam, India. vmoholkar@iitg.ernet.in.
Vijayanand S
VS
Moholkar
ABE fermentation; Biobutanol; Media development; Optimization; Rice straw hydrolysate; Taguchi DOE method