title: Influences of metal ions on microcystin-LR degradation capacity and dynamics in microbial distribution of biofilm collected from water treatment plant nearby Kasumigaura Lake.
abstract: Microcystins-LR (MC-LR) which is a kind of potent hepatotoxin for humans and wildlife can be biodegraded by microbial community. In this study, the capacity of biofilm in degrading MC-LR was investigated with and without additional metal ions (Mn(2+), Zn(2+) and Cu(2+)) at the concentration of 1 mg L(-1). The results indicated that the degradation rate of MC-LR by biofilm was inhibited by introduced Mn(2+) and Cu(2+) during the whole culture period. MC-LR cannot be degraded until a period of culture time passed both in the cases with Zn(2+) and Cu(2+) (2 and 8 days for Zn(2+) and Cu(2+), respectively). The results of mlrA gene analysis showed that the abundance of MC-LR degradation bacteria (MCLDB) in the microbial community under Mn(2+) condition was generally lower than that under no additional metal ion condition. Meanwhile, a two days lag phase for the proliferation of MCLDB occurred after introducing Zn(2+). And a dynamic change of MCLDB from Cu(2+) inhibited species to Cu(2+) promoted species was observed under Cu(2+) condition. The maximum ratio of MCLDB to overall bacteria under various conditions during culture process was found to follow the tendency as: Cu(2+) > Zn(2+) ≈ no additional metal ion (Control) > Mn(2+), suggesting the adverse effect of Mn(2+), no obvious effect of Zn(2+) and positive effect of Cu(2+) on the distribution ratio of MCLDB over the biofilm.
authors.affiliation: School of Environment and Energy, Shenzhen Graduate School of Peking University, Shenzhen, 518055, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan. Electronic address: utsumi.motoo.ge@u.tsukuba.ac.jp.
authors.forename: Motoo
authors.initials: M
authors.lastname: Utsumi
authors.affiliation: College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, PR China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
authors.forename: Qintong
authors.initials: Q
authors.lastname: Li
authors.affiliation: Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Tian
authors.affiliation: Faculty of Life Sciences, Toyo University, 1-1-1 Izumino Ora-gun, Itakura, Gunma, 374-0193, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shimizu
authors.affiliation: Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan; Malaysia-Japan International Institute of Technology (MJIIT)/University Technologi Malaysia, Malaysia.
authors.forename: Norio
authors.initials: N
authors.lastname: Sugiura
mesh_terms: D018407:Bacterial Physiological Phenomena; D001673:Biodegradation, Environmental; D018441:Biofilms; D007564:Japan; D060106:Lakes; D008387:Marine Toxins; D019216:Metals, Heavy / Q000378:metabolism; D052998:Microcystins / Q000378:metabolism*; D018508:Water Purification
chemical_list: D008387:Marine Toxins; D019216:Metals, Heavy; D052998:Microcystins; C057862:cyanoginosin LR
keywords: Biofilm; Metal ion; Microcystins degradation; mlrA