Abstract
The biochemical mechanisms for growth tolerance to a 100% CO headspace in cultures, and butanol plus ethanol production from CO by Butyribacterium methylotrophicum were assessed in the wild-type and CO-adapted strains. The CO-adapted strain grew on glucose or CO under a 100% CO headspace, whereas, the growth of the wild-type strain was severely inhibited by 100% CO. The CO-adapted strain, unlike the wild-type, also produced butyrate, from either pyruvate or CO. The CO-adapted strain was a metabolic mutant having higher levels of ferredoxin–NAD oxidoreductase activity, which was not inhibited by NADH. Consequently, only the CO-adapted strain can grow on CO because CO oxidation generates reduced ferredoxin which, via the mutated ferredoxin–NAD reductase activity, forms reduced NADH required for catabolism. When the CO-adapted strain was grown at pH 6.0 it produced butanol (0.33 g/l) and ethanol (0.5 g/l) from CO and the cells contained the following NAD-linked enzyme activities (μmol min−1 mg protein−1): butyraldehyde dehydrogenase (227), butanol dehydrogenase (686), acetaldehyde dehydrogenase (82) and ethanol dehydrogenase (129).
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Received: 15 September 1998 / Received revision: 12 February 1999 / Accepted: 19 February 1999
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Shen, GJ., Shieh, JS., Grethlein, A. et al. Biochemical basis for carbon monoxide tolerance and butanol production by Butyribacterium methylotrophicum . Appl Microbiol Biotechnol 51, 827–832 (1999). https://doi.org/10.1007/s002530051469
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DOI: https://doi.org/10.1007/s002530051469