Production of butyric acid by a cellulolytic actinobacterium Thermobifida fusca on cellulose
2014
Merklein, Kyle | Fong, Stephen S. | Deng, Yu
Thermobifida fusca not only produces cellulases, hemicellulases and xylanases, but also excretes butyric acid. In order to achieve a high yield of butyric acid, the effect of different carbon sources: mannose, xylose, lactose, cellobiose, glucose, sucrose and acetates, on butyric acid production was studied. The highest yield of butyric acid was 0.67g/gC (g-butyric acid/g-carbon input) on cellobiose. The best stir speed and aeration rate for butyric acid production were found to be 400rpm and 2vvm in a 5-L fermentor. The maximum titer of 2.1g/L butyric acid was achieved on 9.66g/L cellulose. In order to test the production of butyric acid on lignocellulosic biomass, corn stover was used as the substrate, on which there was 2.37g/L butyric acid produced under the optimized conditions. In addition, butyric acid synthesis pathway was identified involving five genes that catalyzed reactions from acetyl-CoA to butanoyl-CoA in T. fusca.
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