Open AccessSuperoxide Dismutase Activity in Pseudomonas putida Affects Utilization of Sugars and Growth on Root Surfaces
Author(s) -
Young Cheol Kim,
Charles D. Miller,
Anne J. Anderson
Publication year - 2000
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.66.4.1460-1467.2000
Subject(s) - superoxide dismutase , pseudomonas putida , mutant , biology , dismutase , biochemistry , superoxide , wild type , oxidative stress , paraquat , catalase , microbiology and biotechnology , enzyme , gene
To investigate the role of superoxide dismutases (SOD) in root colonization and oxidative stress, mutants ofPseudomonas putida lacking manganese-superoxide dismutase (MnSOD) (sodA ), iron-superoxide dismutase (FeSOD) (sodB ), or both were generated. ThesodA sodB mutant did not grow on components washed from bean root surfaces or glucose in minimal medium. ThesodB andsodA sodB mutants were more sensitive than wild type to oxidative stress generated within the cell by paraquat treatment. In single inoculation of SOD mutants on bean, only thesodA sodB double mutant was impaired in growth on root surfaces. In mixed inoculations with wild type, populations of thesodA mutant were equal to those of the wild type, but levels of thesodB mutant and, to a great extent, thesodA sodB mutant, were reduced. Confocal microscopy of young bean roots inoculated with green fluorescent protein-tagged cells showed that wild type and SOD single mutants colonized well predominantly at the root tip but that thesodA sodB double mutant grew poorly at the tip. Our results indicate that FeSOD inP. putida is more important than MnSOD in aerobic metabolism and oxidative stress. Inhibition of key metabolic enzymes by increased levels of superoxide anion may cause the impaired growth of SOD mutants in vitro and in planta.