title: Microbial degradation of microcystin-LR by Ralstonia solanacearum.
abstract: A bacterial strain was isolated from Lake Dianchi (China) and its degradability and degradative pathways of the cyanobacterial toxin microcystin-LR (MC-LR) were studied. On the basis of morphological, physiological and biochemical tests, the strain was identified as Ralstonia solanacearum. The acute oral toxicity tests showed that Ralstonia solanacearum belongs to a non-toxic class. This bacterium degraded MC-LR at the rate of 9.4 mg/L per day, which was higher than those of the other bacterial strains reported in the literature. As for the degradative pathways, the results showed that the Adda-Arg peptide bond of MC-LR was initially hydrolysed by Ralstonia solanacearum to form a linear molecule as an intermediate. The intermediate product subsequently underwent a cyclisation reaction via dehydration to form a final product with a small peptide ring at one end of the molecule. These biodegradative pathways were different from those reported with other bacterial strains, suggesting that MC-LR may undergo different transformations, and different products were formed due to different compositions of bacteria present in natural lakes and reservoirs. These results suggest that there is a significant potential for Ralstonia solanacearum as a degrader for MC-LR removal from wastewater.
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: M L
authors.initials: ML
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Yan
authors.forename: G
authors.initials: G
authors.lastname: Pan
mesh_terms: D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D007700:Kinetics; D008387:Marine Toxins; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D052998:Microcystins / Q000378:metabolism*; D043368:Ralstonia solanacearum / Q000302:isolation & purification / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014871:Water Microbiology
chemical_list: D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR