Enhanced biobutanol production by optimization of the medium from Clostridium acetobutylicum MTCC 11274 using macroalgae Gracilaria edulis

ABSTRACT

Clostridial strain Clostridium acetobutylicum MTCC 11274 was employed for producing biobutanol inbatch culture fermentation. The effects of various carbon sources, i.e., xylose, starch, dextrin, glucose, andmannose as well as nitrogen sources, i.e., yeast extract, peptone, beef extract, and soya protein were studiedconventionally (one-factor-at-a-time). It was found that the maximum amount of biobutanol, i.e., 6.27 and 7.40g/l was obtained from 60 g/l glucose and 5 g/l yeast extract, respectively. In addition to this, the interactionsbetween pH, temperature, and glucose concentration were also taken into consideration for the optimization ofbiobutanol production with the help of Central Composite Design (CCD) of Response Surface Methodology.CCD design was used for the optimization of the above-mentioned parameters and low and high values ofvariables were chosen by performing the steepest ascent experiment. The analysis of variance (ANOVA)model was used for estimating the significance of the model coefficients. ANOVA revealed that the modelwas significant (p < 0.05) and the effects of the glucose concentration, pH, and temperature on biobutanolproduction were significant. It was found that 8.56 g/l biobutanol was produced under optimum fermentationconditions with 40 g/l Gracilaria edulis supplemented with 20 g/l glucose as a carbon source