Table of Contents
ISRN Microbiology
Volume 2013, Article ID 596429, 8 pages
Research Article

Degradation of [ ]MC-LR by a Microcystin Degrading Bacterium Isolated from Lake Rotoiti, New Zealand

1Faculty of Sciences, Khon Kaen University, Khon Kaen 40000, Thailand
2Institute of Food, Nutrition and Human Health, College of Health, Massey University at Wellington, Private Bag 756, Wellington 6140, New Zealand
3Faculty of Engineering, Health, Science and the Environment, Charles Darwin University, Darwin NT 0815, Australia

Received 1 May 2013; Accepted 28 May 2013

Academic Editors: D. A. Daines, V. Juillard, G. G. Olinger, D. Rodriguez-Lazaro, and T. P. West

Copyright © 2013 Theerasak Somdee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


For the first time a microcystin-degrading bacterium (NV-3 isolate) has been isolated and characterized from a NZ lake. Cyanobacterial blooms in New Zealand (NZ) waters contain microcystin (MC) hepatotoxins at concentrations which are a risk to animal and human health. Degradation of MCs by naturally occurring bacteria is an attractive bioremediation option for removing MCs from drinking and recreational water sources. The NV-3 isolate was identified by 16S rRNA sequence analysis and found to have 100% nucleotide sequence homology with the Sphingomonas MC-degrading bacterial strain MD-1 from Japan. The NV-3 isolate (concentration of  CFU/mL) at 30°C degraded a mixture of [Dha7]MC-LR and MC-LR (concentration 25 μg/mL) at a maximum rate of 8.33 μg/mL/day. The intermediate by-products of [Dha7]MC-LR degradation were detected and similar to MC-LR degradation by-products. The presence of three genes (mlrA, mlrB, and mlrC), that encode three enzymes involved in the degradation of MC-LR, were identified in the NV-3 isolate. This study confirmed that degradation of [Dha7]MC-LR by the Sphingomonas isolate NV-3 occurred by a similar mechanism previously described for MC-LR by Sphingomonas strain MJ-PV (ACM-3962). This has important implications for potential bioremediation of toxic blooms containing a variety of MCs in NZ waters.