Biodegradation mechanism of microcystin-LR by a novel isolate of Rhizobium sp. TH and the evolutionary origin of the mlrA geneShow others and affiliations
2016 (English)In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 115, p. 17-25Article in journal (Refereed) Published
Abstract [en]
The frequent presence of microcystin (MC) in eutrophic water bodies worldwide poses a serious threat to ecosystems. Biodegradation has been extensively investigated as a main pathway for MC attenuation, and an mlr-dependent mechanism of MC degradation have been elucidated in detail. However, the evolutionary origin and the distribution of mlr genes in MC-degrading bacteria is poorly understood. In this study, a novel Rhizobium sp. TH, which is the first α-proteobacterial MC-degrading bacterium other than Sphingomonadales, was isolated. Strain TH degraded MC via the mlr-dependent mechanism with a first-order rate constant of 0.18–0.29 h−1 under near-natural conditions. The partial length mlr gene cluster was sequenced, and the function of its key gene, mlrA, was verified by heterologous expression in Escherichia coli. Phylogenetic analyses show that the mlrA gene initially arose in α-proteobacteria by vertical evolution, and the two strains from β- and γ-proteobacteria acquired it by horizontal gene transfer. Therefore, the mlrA gene mainly exists in α-proteobacteria but is seldom present in other bacteria. A pair of primers matching well with mlrA sequences reported so far were designed and could be used to determine the MC-degrading mechanism for novel isolates or to screen for MC-degrading ability among environmental samples.
Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 115, p. 17-25
Keywords [en]
Degradation, Evolutionary origin, Mechanism, Microcystin, mlrA gene, Rhizobium, Bacteria, Escherichia coli, Gene expression, Gene transfer, Genes, Mechanisms, Rate constants, Strain, Toxic materials, Environmental sample, First-order rate constants, Heterologous expression, Horizontal gene transfer, Microcystins, Phylogenetic analysis, Biodegradation, eutrophic environment, evolutionary biology, gene, phylogenetics, reaction kinetics, rhizobacterium, toxin, Alphaproteobacteria, Bacteria (microorganisms), Gammaproteobacteria, Proteobacteria, Rhizobium sp., Sphingomonadales
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:kth:diva-195227DOI: 10.1016/j.ibiod.2016.07.011ISI: 000388048700003Scopus ID: 2-s2.0-84979710830OAI: oai:DiVA.org:kth-195227DiVA, id: diva2:1047357
Note
QC 20161117
2016-11-172016-11-022022-06-27Bibliographically approved