Citation

Abbad-Andaloussi S, Manginot-Durr C, Amine J, Petitdemange E, Petitdemange H. Appl. Environ. Microbiol. 1995; 61(12): 4413-4417.

Copyright

(Copyright © 1995, American Society for Microbiology)

DOI

10.1128/aem.61.12.4413-4417.1995

PMID

unavailable

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.

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.

Language: en

Keywords

acetic acid; article; nonhuman; enzyme activity; Bacteria (microorganisms); glycerol; 1,3 propanediol; fermentation; hydrogenase; bacterium mutant; bacterial metabolism; bacterium isolation; butyric acid; carboxylic acid; Clostridium butyricum; ferredoxin; nicotinamide adenine dinucleotide; phosphotransferase; reduced nicotinamide adenine dinucleotide