Isolation of carotenoid-deficient mutant from alkylated dibenzothiophene desulfurizing nocardioform bacteria, Gordonia sp. TM414.

The dibenzothiophene-desulfurizing nocardioform bacteria, Gordonia sp. TM414, was isolated from oil-contaminated soil. To avoid coloration of the oil layer after the desulfurization reaction, which could decrease the quality of the oil, two colorless knock-out mutants, TPc and TPd, were isolated by using a broad-host-range transposon complex. Genomic sequence analysis revealed that the same gene was disrupted in these mutants and that the transposon-inserted gene was assigned as the gene for phytoene desaturase, crt I. The crt I mutants also showed desulfurization activity comparable to that of the parent strain in a model-oil/aqueous bi-phasic reaction, suggesting that the carotenoid production is not responsible for the bi-phasic desulfurization reaction that requires hydrophobic substrate incorporation from the organic phase.