title: Cyanotoxin degradation activity and mlr gene expression profiles of a Sphingopyxis sp. isolated from Lake Champlain, Canada.
abstract: A bacterium capable of degrading five microcystin (MC) variants, microcystin-LR, YR, LY, LW and LF at an initial total concentration of 50 μg l-1in less than 16 hours was isolated from Missisquoi Bay, in the south of Quebec, Canada. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Sphingopyxis sp., designated strain MB-E. It was shown that microcystin biodegradation activity was reduced at acidic and basic pH values. Even though no biodegradation occurred at pH values of 5.05 and 10.23, strain MB-E was able to degrade MCLR and MCYR at pH 9.12 and all five MCs variants tested at pH 6.1. Genomic sequencing revealed that strain MB-E contained the microcystin degrading gene cluster, including the mlrA, mlrB, mlrC and mlrD genes, and transcriptomic analysis demonstrated that all of these genes were induced during the degradation of MCLR alone or in the mixture of all five MCs. This novel transcriptomic analysis showed that the expression of the mlr gene cluster was similar for MCLR alone, or the mixture of MCs, and appeared to be related to the total concentration of substrate. The results suggested that the bacterium used the same pathway for the degradation of all MC variants.
authors.affiliation: Polytechnique Montreal, Civil, Mineral and Mining Engineering Department, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec, Canada H3C 3A7. ehsan.maghsoudi@polymtl.ca.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Maghsoudi
authors.affiliation: National Research Council Canada, Energy, Mining and Environment, 6100 Royalmount Ave., Montreal, QC, Canada H4P 2R2.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fortin
authors.affiliation: National Research Council Canada, Energy, Mining and Environment, 6100 Royalmount Ave., Montreal, QC, Canada H4P 2R2.
authors.forename: Charles
authors.initials: C
authors.lastname: Greer
authors.affiliation: Department of Natural Resource Sciences, McGill University, 21,111 Lakeshore, Ste-Anne-de-Bellevue, QC, Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Maynard
authors.affiliation: Department of Natural Resource Sciences, McGill University, 21,111 Lakeshore, Ste-Anne-de-Bellevue, QC, Canada.
authors.forename: Antoine
authors.initials: A
authors.lastname: Pagé
authors.affiliation: Department of Chemistry, Université de Montreal, C.P. 6128, Centre-Ville, Montreal, QC, Canada H3C 3J7.
authors.forename: Sung Vo
authors.initials: SV
authors.lastname: Duy
authors.affiliation: Department of Chemistry, Université de Montreal, C.P. 6128, Centre-Ville, Montreal, QC, Canada H3C 3J7.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.affiliation: Polytechnique Montreal, Civil, Mineral and Mining Engineering Department, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec, Canada H3C 3A7. ehsan.maghsoudi@polymtl.ca.
authors.forename: Michèle
authors.initials: M
authors.lastname: Prévost
authors.affiliation: Polytechnique Montreal, Civil, Mineral and Mining Engineering Department, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec, Canada H3C 3A7. ehsan.maghsoudi@polymtl.ca.
authors.forename: Sarah
authors.initials: S
authors.lastname: Dorner
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001673:Biodegradation, Environmental; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D060106:Lakes / Q000382:microbiology*; D052998:Microcystins / Q000378:metabolism*; D011792:Quebec; D042301:Sphingomonadaceae / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D059467:Transcriptome; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D052998:Microcystins; D014874:Water Pollutants, Chemical