title: Dynamics of the functional gene copy number and overall bacterial community during microcystin-LR degradation by a biological treatment facility in a drinking water treatment plant.
abstract: Information is limited on the potential for microcystins (MCs) degradation by carrier-attached biofilms obtained in winter that were not exposed to detectable levels of MCs in the preceding months. Under controlled laboratory conditions, we confirmed that microcystin-LR (MCLR) was effectively biodegraded within 5.5 days in cultures of the biofilm sampled in winter. Quantitative polymerase chain reaction (qPCR) assays revealed that seasonal variations in the MCLR-degradation potential of the biofilm were closely related to the initial MCLR-degrader population in the biofilm. Indigenous MCLR-degraders in the biofilm could accumulate by exposure to natural MCLR in the water column, accelerating MCLR-degradation. The qPCR assay suggested that MCLR may be a primary substrate for the degraders in the presence of another labile organic carbon associated with the biofilm under the present study conditions. qPCR and PCR-denaturing gradient gel electrophoresis (DGGE) for 16S rDNA demonstrated that the overall bacterial population from the winter biofilm rapidly increased with the MCLR-degrader population and remained stable after day 3.5, while the overall bacterial community structure shifted throughout the entire biodegradation period. This study is important to the in-depth understanding of microbial degradation of MCs and could facilitate the bioremediation of MCs in polluted habitats.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Jieming
authors.initials: J
authors.lastname: Li
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shimizu
authors.forename: Motoo
authors.initials: M
authors.lastname: Utsumi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakamoto
authors.forename: Meena Kishore
authors.initials: MK
authors.lastname: Sakharkar
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Zhang
authors.forename: Norio
authors.initials: N
authors.lastname: Sugiura
mesh_terms: D001419:Bacteria / Q000235:genetics* / Q000378:metabolism; D001673:Biodegradation, Environmental; D018441:Biofilms; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D005068:Eutrophication; D005618:Fresh Water / Q000032:analysis; D018628:Gene Dosage; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000378:metabolism; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D004269:DNA, Bacterial; D008387:Marine Toxins; D052998:Microcystins; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C057862:cyanoginosin LR