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  • 1
    Electronic Resource
    Electronic Resource
    Biochemical basis for carbon monoxide tolerance and butanol production by Butyribacterium methylotrophicum (1999)
    Springer
    Applied microbiology and biotechnology 51 (1999), S. 827-832 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 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).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051469
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Regulation of hydrogen metabolism in Butyribacterium methylotrophicum by substrate and pH (1996)
    Springer
    Applied microbiology and biotechnology 45 (1996), S. 804-810 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Exogenous H2/CO2 and glucose were consumed simultaneously by Butyribacterium methylotrophicum when grown under glucose-limited conditions. CO2 reduction to acetate was coupled to H2 consumption. The addition of either H2 or CO2 to glucose batch fermentation resulted in an increase in cell density, hydrogenase (H2-consuming and -producing) activities and fatty acid production by B. methylotrophicum as compared to when N2 was the feed gas. Hydrogenase activities appeared to be tightly regulated and were produced at higher rates during the exponential phase when CO2 was the feed gas as compared to H2 or N2. The increase in H2-consuming activity and decrease in H2-producing activity was correlated with an increase in butyrate synthesis. H2-consuming and ferredoxin (Fd)–NAD reductase activities increased while H2-producing and NADH–Fd reductase activities decreased in cells grown at pH 5.5 compared to those at pH 7.0. The molar ratio of butyrate/acetate was shifted from 0.35 at pH 7.0 to 1.22 at pH 5.5. The addition of exogenous H2 did not decrease the butyrate/acetate ratio at pH 7.0 nor at pH 5.5. The results indicated that growth pH values regulated both hydrogenase and Fd–NAD oxidoreductase activities such that, at acid pH, more intermediary electron flow was directed towards butyrate synthesis than H2 production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050766
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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