(471e) Enhance L-(+) Lactic Acid Production Using Pelletized Rhizopus Oryzae

Producing lactic acid from biomass has attracted increasing interests and the use of lactic acid expands from food industries as flavor and preservation to pharmaceutical and cosmetic industries as lactate polymer plastics and to polymer and textile industry biodegradable plastics. A novel fungal fermentation process was developed to produce optical pure L-(+) lactic acid from cull potato and glucose by a pelletized filamentous fungus, Rhizopus oryzae NRRL 395. Multiple logistic regression models were used to predict the pellet formation process. The fungal morphology was controlled to small pellets to improve the performance of bioreactor in terms of mass transfer and operational facility. Strategies of improving lactic acid production in terms of yield, productivity and concentration in broth were evaluated. Nutrient-rich cull potato medium was used to cultivate the pellet seed for high density fermentation to achieve high productivity (>2g/L/h). Depriving the cells of some essential nutrient such as nitrogen was used to increase the observed yield from substrate (>66%). High soluble lactate concentration in broth was obtained by fed-batch culture using mix alkali to neutralize the pH ( >90g/L). Finally, the lactic acid production was performed efficiently by combining above strategies using a repeated batch culture. The total energy cost of fermentation process was predicted using Matlab Simulink. The possibility of commercialization of this process was discussed.