Bacterial degradation of microcystin toxins within a biologically active sand filter

• Published in: Water research (Oxford) Vol. 40; no. 4; pp. 768 - 774
• Main Authors: Ho, Lionel, Meyn, Thomas, Keegan, Alexandra, Hoefel, Daniel, Brookes, Justin, Saint, Christopher P., Newcombe, Gayle
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2006; Elsevier Science
• Subjects: Applied sciences; Bacterial Toxins; biodegradation; biofilm; Biofilms; Biological sand filtration; biological treatment; biologically active sand filters; Degradation; DNA, Bacterial - analysis; DNA, Bacterial - genetics; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; filters; Filtration; genes; Microcystin; microcystin-LA; microcystin-LR; Microcystins; MlrA gene; Peptides, Cyclic - metabolism; Pollution; pollution control; Polymerase Chain Reaction; sand; Silicon Dioxide; Sphingomonadaceae - genetics; Sphingomonadaceae - physiology; water pollution; Water Purification - methods; water treatment; Water treatment and pollution; Australia; Oceania; Degradation; Polymerase chain reaction; Microcystin; Biological sand filtration; MlrA gene; Biodegradation; Drinking water treatment; Microcystis aeruginosa; Water filtration; Cyclic peptides; Toxin; Biological sand filtration Degradation Microcystin MlrA gene Polymerase chain reaction; Sand filter; Decontamination; Microbial origin; Polypeptide; Artificial lake; Pathogenic; Cyanobacteria; Biofilm; Bacteria; Control method; Water pollution; Biological treatment
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.12.009

Microcystin toxins are a problem for water authorities as they are recalcitrant to conventional water treatment. In this study, biological sand filtration was assessed in laboratory column experiments for its ability to remove two microcystin analogues, microcystin-LR and microcystin-LA. A lag period of 3 days was evident prior to the commencement of degradation. Contact times were varied during the experiment; however, no microcystin was detected in the effluent after 4 days, even under conditions similar to those of a rapid sand filter. Removals of microcystin through the sand filters were shown to be primarily through biological degradation processes. Using polymerase chain reaction (PCR), biofilm, extracted from one of the sand filters that had effectively removed the microcystins, was shown to contain bacteria with the mlrA gene. Detection of this gene provided additional evidence that biological degradation of microcystin was the primary removal mechanism.