Effects of cultivation parameters on the morphology of Rhizopus arrhizus and the lactic acid production in a bubble column reactor
Date
2007
Authors
Zhang, Z.
Jin, B.
Kelly, J.
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Type:
Journal article
Citation
Engineering in Life Sciences, 2007; 7(5):490-496
Statement of Responsibility
Z.Y. Zhang, B. Jin, J.M. Kelly
Conference Name
Abstract
The use of filamentous Rhizopus for lactic acid production is facing a challenge due to its low yield mainly caused by the difficulty to control its morphology in submerged fermentation processes. This study was aimed at investigating the impacts of cultivation parameters on the morphology of Rhizopus arrhizus DAR 36017 and lactic acid production using waste potato starch in a laboratory scale bubble column reactor (BCR). The fungal morphology was significantly influenced by carbon sources, process pH, starch concentrations, sparger designs and aeration rates. The favorable morphology for lactic acid production was a freely dispersed small pellet, which was achieved under operation conditions at pH 5.0-6.0, starch concentrations of 60-120 g/L and aeration rates of 0.2-0.8 vvm using a sintered stainless steel disc sparger. Optimal cultivation conditions at pH 6.0 and an aeration rate of 0.4 vvm resulted in the formation of freely dispersed small pellets and 103.8 g/L lactic acid with a yield of 87 % from 120 g/L liquefied potato starch in 48 h. The overall results in terms of lactic acid yield and productivity are comparable to those reported in previous studies using immobilized Rhizopus cells in batch fermentations.
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Description
The definitive version may be found at www.wiley.com Australian Research Council Discovery grant; Grant Number: DP0452516