title: Genetic dissection of chlorate respiration in Pseudomonas stutzeri PDA reveals syntrophic (per)chlorate reduction.
abstract: Genes important for growth of Pseudomonas stutzeri PDA on chlorate were identified using a randomly DNA bar-coded transposon mutant library. During chlorate reduction, mutations in genes encoding the chlorate reductase clrABC, predicted molybdopterin cofactor chaperon clrD, molybdopterin biosynthesis and two genes of unknown function (clrE, clrF) had fitness defects in pooled mutant assays (Bar-seq). Markerless in-frame deletions confirmed that clrA, clrB and clrC were essential for chlorate reduction, while clrD, clrE and clrF had less severe growth defects. Interestingly, the key detoxification gene cld was essential for chlorate reduction in isogenic pure culture experiments, but showed only minor fitness defects in Bar-seq experiments. We hypothesized this was enabled through chlorite dismutation by the community, as most strains in the Bar-seq library contained an intact cld. In support of this, Δcld grew with wild-type PDA or ΔclrA, and purified Cld also restored growth to the Δcld mutant. Expanding on this, wild-type PDA and a Δcld mutant of the perchlorate reducer Azospira suillum PS grew on perchlorate in co-culture, but not individually. These results demonstrate that co-occurrence of cld and a chloroxyanion reductase within a single organism is not necessary and raises the possibility of syntrophic (per)chlorate respiration in the environment.
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, CA, 94720, USA.
authors.forename: Iain C
authors.initials: IC
authors.lastname: Clark
authors.affiliation: Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
authors.forename: Matt
authors.initials: M
authors.lastname: Youngblut
authors.affiliation: Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
authors.forename: Gillian
authors.initials: G
authors.lastname: Jacobsen
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Wetmore
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Deutschbauer
authors.affiliation: Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Lucas
authors.affiliation: Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA. jdcoates@berkeley.edu.
authors.forename: John D
authors.initials: JD
authors.lastname: Coates
mesh_terms: D002704:Chlorates / Q000378:metabolism*; D003067:Coenzymes / Q000096:biosynthesis; D004251:DNA Transposable Elements; D008667:Metalloproteins / Q000096:biosynthesis; D000090006:Molybdenum Cofactors; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics*; D010472:Perchlorates / Q000378:metabolism*; D044223:Pseudomonas stutzeri / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D011621:Pteridines; D043362:Rhodocyclaceae / Q000254:growth & development / Q000378:metabolism
chemical_list: D002704:Chlorates; D003067:Coenzymes; D004251:DNA Transposable Elements; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D010088:Oxidoreductases; D010472:Perchlorates; D011621:Pteridines; C022261:molybdopterin; C021777:chlorate reductase; C494474:perchlorate