Fermentation characteristics of Clostridium pasteurianum LMG 3285 grown on glucose and mannitol |
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Authors: | M. Heyndrickx P. De Vos J. De Ley |
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Affiliation: | Laboratorium voor Microbiologie en microbiële Genetica, Rijksuniversiteit Gent, Belgium |
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Abstract: | Clostridium pasteurianum fermented glucose to acetate, butyrate, CO2 and H2. In batch cultures the fermentation pattern was only slightly affected by culture pH over the range 8·0 to 5·5. The acetate/butyrate ratio was always higher than or equal to one. Between 2·14 and 2·33 mol H2 was produced per mol glucose fermented. At unregulated pH, more butanol and less butyrate was formed. In a carbon-limited chemostat, the steady-state acetate/butyrate ratio was always lower than one. H2 production was approximately 1·70 mol per mol glucose consumed. Substantial amounts of extracellular protein were formed. With decreasing pH, acetate and formate production decreased, while H2 production was highest at pH 6.0. With increasing dilution rate ( D ), the product spectrum hardly changed, but more biomass was formed. Y glucosemax and Y ATPmax were 55·97 and 31·48 g dry weight per mol glucose or ATP respectively. With increasing glucose input the formation of fatty acids and H2 slightly decreased. Continuous cultures fermented mannitol to acetate, butyrate, butanol, CO2 and H2. With acetate as co-substrate, butanol production and molar growth yields, Y mannitol and Y ATP, markedly decreased, while the butyrate and H2 production increased. The latter reached a value of 2·21 mol H2 per mol mannitol consumed. |
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