@article{ref1,
title="Isolation and characterization of Clostridium butyricum DSM 5431 mutants with increased resistance to 1,3-propanediol and altered production of acids",
journal="Applied and environmental microbiology",
year="1995",
author="Abbad-Andaloussi, S. and Manginot-Durr, C. and Amine, J. and Petitdemange, E. and Petitdemange, H.",
volume="61",
number="12",
pages="4413-4417",
abstract="Clostridium butyricum mutants were isolated from the parent strain DSM 5431 after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and two selection procedures: osmotic pressure and the proton suicide method. Isolated mutants were more resistant to glycerol and to 1,3-propanediol (1,3- PD) than was the wild type, and they produced more biomass. In batch culture on 62 g of glycerol per liter, the wild type produced more acetic acid than butyrate, with an acetate/butyrate ratio of 5.0, whereas the mutants produced almost the same quantities of both acids or more butyrate than acetate with acetate/butyrate ratios from 0.6 to 1.1. The total acid formation was higher in the wild-type strain. <br><br>RESULTS of analysis of key metabolic enzymatic activities were in accordance with the pattern of fermentation product formation: either the butyrate kinase activity increased or the acetate kinase activity decreased in cell extracts of the mutants. A decreased level of the hydrogenase and NADH-ferredoxin activities concomitant with an increase in ferredoxin-NAD+ reductase activities supports the conclusion that the maximum percentage of NADH available and used for the formation of 1,3-PD was higher fur the mutants (97 to 100%) than for the wild type (70%). In fed-batch culture, at the end of the fermentation (72 h for the wild-type strain and 80 to 85 h for the mutants), 44% more glycerol was consumed and 50% more 1,3-PD was produced by the mutants than by the wild-type strain.<p /><p>Language: en</p>",
language="en",
issn="0099-2240",
doi="10.1128/aem.61.12.4413-4417.1995",
url="http://dx.doi.org/10.1128/aem.61.12.4413-4417.1995"
}