Sunday, May 3, 2009
6-13
Optimization of lactic acid production by pelleted-form of Rhizopus oryzae in 3 L airlift bioreactor using response surface methodology
Thanapoom Maneeboon1, Wirat Vanichsriratana2, Chaiyaporn Promchaitaward3, and Vichien Kitpreechavanich1. (1) Department of Microbiology,Faculty of Science, Kasetsart University, Phahonyothin Rd., Jatujak, Bangkok, 10900, Thailand, (2) Derpartment of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Phahonyothin Rd., Jatujak, Bangkok, 10900, Thailand, (3) National Metal and Materials Technology Center 114 Thailand Science Park, Pathumthani, 12120, Thailand
Lactic acid production by pelleted-form Rhizopus oryzae was optimized in 3 l airlift bioreactor. The effect of pH and volumetric oxygen transfer efficiency (kLa) was evaluated according to the 23 central composite designs. Results of regression analysis suggested linear and quadratic terms of pH and kLa were significant affected on lactic acid. Ethanol formation was found that it depends on linear and quadratic terms of pH and only linear term of kLa. Whereas quadratic term of pH and kLa were significant affected on biomass. Interaction between pH and kLa were not influenced on considered variables. From response surface analysis, optimal pH and kLa were 5.85 and of 0.065 s-1, respectively and lactic acid of 72.10 g/l was achieved. Subsequently, successive five repeated batches with average 77.54 g/l of lactic acid were achieved and lactic acid productivity was improved from 0.75 to 0.99 g/l h.