Optimization of culture conditions for CO 2 fixation by a chemoautotrophic microorganism, strain YN-1 using factorial design

Abstract

Culture conditions for CO 2 fixation by a chemoautotrophic microorganism, strain YN-1, were optimized by statistical analysis using factorial design. Statistical analysis was performed by SAS software and then predicted the levels of four factors, H 2 ( X 1), O 2 ( X 2), CO 2 ( X 3) concentration and pH ( X 4) which were required to obtain the optimum culture conditions. For the fractional factorial design 3 4−1, total 27 experimental runs by combination of each factor were carried out in a 5 L-jar fermentor, and the three-dimensional response surfaces were plotted to find out the optimum level of each factor for maximum CO 2 fixation. Dry cell weight in optimized culture condition was predicted as 11.4 g/L in 48 h under the condition of 37.5 × 10 −3 mol/min H 2, 9.38 × 10 −3 mol/min O 2, 4.91 × 10 −3 mol/min CO 2, and pH 6.7. As compared with CO 2 fixation rate before optimizing culture conditions, the improvement of CO 2 fixation rate under optimized culture conditions was experimentally confirmed.