Competitiveness in root colonization by Pseudomonas putida requires the rpoS gene.
Miller, Charles D; Kim, Young-Cheol; Anderson, Anne J
[Article] Canadian Journal of Microbiology. 47(1):41-48, January 2001.

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The rpoS gene in Pseudomonas putida was essential for plant root colonization under competitive conditions from other microbes. The RpoS- mutant survived less well than the wild-type strain in culture medium, and unlike the wild-type, failed to colonize the roots in a peat matrix containing an established diverse microflora. The RpoS-deficient P. putida isolate was generated by insertion of a glucuronidase-npt cassette into the rpoS gene. The RpoS- mutant had dose-dependent increased sensitivity to oxidative stress and produced Mn-superoxide dismutase activity earlier than the parent. While extracts from wild-type P. putida stationary-phase cells contained three isozymes of catalase (CatA, CatB, and CatC), the [sigma]38-deficient P. putida lacked CatB. These results are consistent with previous findings that CatB is induced in stationary-phase.

(C) 2001 National Research Council Canada