Australian Water Quality Centre, South Australian Water Corporation, 250 Victoria Square, Adelaide, SA 5000, Australia.
Chemosphere. 2012 Jun;87(10):1149-54. doi: 10.1016/j.chemosphere.2012.02.020. Epub 2012 Mar 3.
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.
在两个澳大利亚水源中评估了多种蓝藻代谢物的命运。结果表明，萨克斯毒素是唯一在迈普onga 水库水中不可生物降解的代谢物，而微囊藻毒素-LR（MCLR）和土臭素在该水源中可生物降解。同样，柱孢藻毒素（CYN）在 Murray 河水中可生物降解。生物降解的容易程度顺序为：MCLR>CYN>土臭素>萨克斯毒素。代谢物的生物降解受温度和季节性变化的影响，在 24°C 时和秋季比在 14°C 时和冬季降解速度更快。分离出一种能够降解微囊藻毒素的细菌，并在 4 小时内降解了四种微囊藻毒素变体。这种细菌被命名为 TT25，根据 16S rRNA 基因片段，与 Sphingopyxis sp. 相似度达到 99%。分离株 TT25 含有 mlrA 基因的同源物；其序列与先前报道的微囊藻降解菌的序列 99%相似。此外，在硫酸铜（0.5mg/L 作为 Cu(2+)）存在下，TT25 能够降解微囊藻毒素，这对水务部门在水中投加这种杀藻剂以控制蓝藻水华是有利的。
