title: Bacterial degradation of microcystin toxins within a biologically active sand filter.
abstract: 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.
authors.affiliation: Cooperative Research Centre for Water Quality and Treatment, Australian Water Quality Centre, SA Water Corporation, PMB 3, Hodgson Rd, Bolivar, Salisbury, SA 5108, Australia. lionel.ho@sawater.com.au
authors.forename: Lionel
authors.initials: L
authors.lastname: Ho
authors.forename: Thomas
authors.initials: T
authors.lastname: Meyn
authors.forename: Alexandra
authors.initials: A
authors.lastname: Keegan
authors.forename: Daniel
authors.initials: D
authors.lastname: Hoefel
authors.forename: Justin
authors.initials: J
authors.lastname: Brookes
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Saint
authors.forename: Gayle
authors.initials: G
authors.lastname: Newcombe
mesh_terms: D001427:Bacterial Toxins; D018441:Biofilms; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005374:Filtration; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012822:Silicon Dioxide; D042301:Sphingomonadaceae / Q000235:genetics / Q000502:physiology; D018508:Water Purification / Q000379:methods*
chemical_list: D001427:Bacterial Toxins; D004269:DNA, Bacterial; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; D012822:Silicon Dioxide; C049865:cyanoginosin-LA; C057862:cyanoginosin LR