Isolation and characterization of toluene-sensitive mutants from Pseudomonas putida IH-2000

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• 作者：Hirayama ; Hisako ; Takami ; Hideto ; Inoue ; Akira ; Horikoshi ; Koki
• 关键词：Pseudomonas putida IH-2000 ; Tn5 transposon mutagenesis ; cyoABCDE ; Cytochrome o ; Toluene tolerance
• 刊名：FEMS Microbiology Letters
• 出版年：1998
• 出版时间：December 15, 1998
• 年：1998
• 卷：169
• 期：2
• 页码：219-225
• 全文大小：1019 K

文摘

Two toluene-sensitive mutants were generated from Pseudomonas putida IH-2000, the first known toluene-tolerant isolate, by Tn5 transposon mutagenesis. These mutants were unable to grow in the presence of toluene (log P_ow 2.8) but they could grow in medium overlaid with organic solvents having a log P_ow value higher than that of toluene such as p-xylene (log P_ow 3.1), cyclohexane (log P_ow 3.4) and n-hexane (log P_ow 3.9). The Tn5 transposable element knocked out a cyoB-like gene in one mutant and a cyoC-like gene in the other mutant. Seven open reading frames were found in a 5.5-kb region containing the cyoB- and cyoC-like genes of strain IH-2000. ORFs 3–7 showed significant identity to the cyoABCDE gene products of Escherichia coli, but ORFs 1 and 2 showed no significant homology to any protein reported so far. The growth patterns of the Tn5 mutants with the inactivated cyo-like gene were similar to that of the wild-type strain in the absence of organic solvents, although the doubling times were slightly longer than that of the wild-type strain. Our findings indicate that cyo is an important gene for toluene tolerance, although its role is still unclear.