AWWA WQTC65934

Microcystins are potent hepatotoxins which are produced in water supplies by blue-green algae (cyanobacteria). In dissolved (extracellular) form, microcystins are not efficiently removed by conventional water treatment processes. This study focused on the removal of microcystins from drinking water using biological sand and granular activated carbon (GAC) filtration processes. The results indicate that these toxins were effectively removed in a range of biological filters and that a specific bacterium was responsible for the degradation through the sand filters. Batch degradation experiments were performed using this bacterium to confirm that it could degrade microcystins. Furthermore, these batch experiments demonstrated that no toxic byproducts were generated during the biodegradation of the microcystins, with toxicity assessed by a protein phosphatase inhibition assay and a cell culture cytotoxicity assay. Molecular techniques were also used to detect the presence of a gene, mlrA, previously shown to be involved in the degradation of microcystin toxins. This gene was detected within the genome of the aforementioned bacterium providing additional evidence that removal of microcystins was through biodegradation. The isolated bacterium was shown to belong to the family Sphingomonadaceae using phylogenetic methods. Includes 34 references, tables, figures.