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Vol. 75, No. 21, 2009; Pages: 6924–6928

Isolation and Identification of Novel Microcystin-Degrading Bacteria

Pathmalal M. Manage,1 Christine Edwards,2 Brajesh K. Singh,3 and Linda A. Lawton2*

School of Pharmacy and Life Sciences, The Robert Gordon University, Aberdeen, United Kingdom AB25 1HG.


Of 31 freshwater bacterial isolates screened using the Biolog MT2 assay to determine their metabolism of the microcystin LR, 10 were positive. Phylogenetic analysis (16S rRNA) identified them as Arthrobacter spp., Brevibacterium sp., and Rhodococcus sp. This is the first report of microcystin degraders that do not belong to the Proteobacteria. A number of studies have reported biological degradation of microcystin in samples from lakes and sediments (3, 4, 12, 15), but only a few bacterial strains with the ability to degrade microcystins have been isolated and characterized (6). Previously identified bacteria belonged to the Proteobacteria, and with the exception of one isolate (Sphingomonas sp. strain CB4), they were all shown to degrade microcystin LR (MCLR) via the same degradation pathway: formation of linear MC-LR following cleavage at the 3-amino-9-methoxy-2,6,8- trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda)–Arg bond and hydrolysis at Ala-Leu to yield a tetrapeptide with Adda as the final product detected (1, 10, 11). Genes encoding enzymes involved in this pathway have been characterized and shown to have similarity in all bacterial isolates currently reported to degrade microcystins (2).

Keywords:Arthrobacter spp., Brevibacterium sp., Rhodococcus sp,Proteobacteria,Paucibacter toxinivorans,physiology.

Corresponding author: Tel 44 (0) 1224262823, Fax 44 (0) 1224262828.

E-mail: l.lawton@rgu.ac.uk


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