Two different electron transfer pathways may involve in azoreduction in Shewanella decolorationis S12.
Electron transfer pathways for azoreduction by S. decolorationis S12 were studied using a mutant S12-22 which had a transposon insertion in ccmA. The results imply that there are two different pathways for electron transport to azo bonds. The colony of S12-22 was whitish and incapable of producing mature c-type cytochromes whose alpha-peak was at 553 nm in the wild type S12. The mutant S12-22 could not use formate as the sole electron donor for azoreduction either in vivo or in vitro, but intact cells of S12-22 were able to reduce azo dyes of low polarity, such as methyl red, when NADH was served as the sole electron donor. Although the highly polar-sulfonated amaranth could not be reduced by intact cells of S12-22, it could be efficiently reduced by cell extracts of the mutant when NADH was provided as the sole electron donor. These results suggest that the mature c-type cytochromes are essential electron mediators for the extracellular azoreduction of intact cells, while the other pathway without the involvement of mature c-type cytochromes, NADH-dependent oxidoreductase-mediated electron transfer pathway can reduce lowly polar sulfonated azo dyes inside the whole cells or highly polar sulfonated azo dyes in the cell extracts without bacterial membrane barriers.
Chen
Xingjuan
X
South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
Xu
Meiying
M
Wei
Jinbo
J
Sun
Guoping
G
D001391:Azo Compounds / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D004396:Coloring Agents / Q000378:metabolism*; D004251:DNA Transposable Elements; D004583:Electrons; D005561:Formates / Q000378:metabolism; D017353:Gene Deletion; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism*
D001391:Azo Compounds; D001425:Bacterial Outer Membrane Proteins; C118373:CcmA protein, bacteria; D004396:Coloring Agents; D004251:DNA Transposable Elements; D005561:Formates; D009243:NAD; C030544:formic acid