Comparison of L-lactic acid production by Bacillus coagulans and Rhizopus oryzae with fiber waste

L-lactic acid can be produced from sugar by anaerobic fermentation with homolactic acid bacteria and aerobic fermentation with filamentous fungus. In order to show the potentiality of anaerobic Bacillus coagulans and aerobic Rhizopus oryzae to produce L-lactic acid from renewable screened fiber waste from NaOH-AQ pulping process, the comparisons of Bacillus coagulans and Rhizopus oryzae in the Simultaneous Saccharification and Fermentation process was investigated. Factors influencing the yield and purity of L-lactic acid, including seed culture medium, incubation time, fermentation culture, fermentation temperature, fermentation time, inoculums amount, oxygen requirement, were discussed. The results showed that both Bacillus coagulans and Rhizopus oryzae can be utilized for the production of the L-lactic acid from the renewable fiber waste from the pulping process, but regarding the yield and the purity of L-lactic acid, Bacillus coagulans was a better and more promising strain.