title: Biodegradation of multiple cyanobacterial metabolites in drinking water supplies.
abstract: The fate of multiple cyanobacterial metabolites was assessed in two Australian source waters. The saxitoxins were the only metabolites shown to be non-biodegradable in Myponga Reservoir water, while microcystin-LR (MCLR) and geosmin were biodegradable in this water source. Likewise, cylindrospermopsin (CYN) was shown to be biodegradable in River Murray water. The order of ease of biodegradability followed the trend: MCLR>CYN>geosmin>saxitoxins. Biodegradation of the metabolites was affected by temperature and seasonal variations with more rapid degradation at 24°C and during autumn compared with 14°C and during winter. A microcystin-degrading bacterium was isolated and shown to degrade four microcystin variants within 4 h. This bacterium, designated as TT25, was shown to be 99% similar to a Sphingopyxis sp. based on a 16S rRNA gene fragment. Isolate TT25 was shown to contain a homologue of the mlrA gene; the sequence of which was 99% similar to that of a previously reported microcystin-degrader. Furthermore, isolate TT25 could degrade the microcystins in the presence of copper sulphate (0.5 mg L(-1) as Cu(2+)) which is advantageous for water authorities dosing such algicides into water bodies to control cyanobacterial blooms.
authors.affiliation: Australian Water Quality Centre, South Australian Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia. lionel.ho@sawater.com.au
authors.forename: Lionel
authors.initials: L
authors.lastname: Ho
authors.forename: Tim
authors.initials: T
authors.lastname: Tang
authors.forename: Paul T
authors.initials: PT
authors.lastname: Monis
authors.forename: Daniel
authors.initials: D
authors.lastname: Hoefel
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000378:metabolism*; D000087522:Cyanobacteria Toxins; D060766:Drinking Water / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005798:Genes, Bacterial / Q000235:genetics; D008387:Marine Toxins / Q000737:chemistry / Q000378:metabolism*; D052998:Microcystins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012621:Seasons; D013021:South Australia; D042301:Sphingomonadaceae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D060766:Drinking Water; D008387:Marine Toxins; D052998:Microcystins; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C078588:microcystin