title: Comparative study for the effects of variable nutrient conditions on the biodegradation of microcystin-LR and concurrent dynamics in microcystin-degrading gene abundance.
abstract: Microcystin-LR (MCLR) degradation capability of biofilm was investigated with and without additional nutrients (nitrate, ammonium, peptone and glucose) at concentrations of 100 and 1000 mg L(-1). The MCLR-degradation was stimulated with nitrate and inhibited with other nutrients, except for that glucose of low concentration had no obvious effect. Both stimulatory and inhibitory effects enhanced with increasing concentration of corresponding nutrient. Quantitative polymerase chain reaction (qPCR) indicated that enhanced inhibition in biodegradation correlated to increased inhibition in functional gene (mlrA) abundance, as nutrient concentration increased. Stimulated biodegradation under low nitrate concentration may result from more rapid increase in mlrA gene abundance. These suggested that MCLR-degradation largely depended upon responsible bacterial population, which was affected by population of other bacteria in biofilm according to 16S rDNA-targeting qPCR. However, inhibited mlrA gene abundance implied that the stimulated biodegradation under high nitrate concentration might be involved in the mechanisms not related to MCLRDB population.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Tennodai 1-1-1, Ibaraki 3058572, Japan.
authors.forename: Jieming
authors.initials: J
authors.lastname: Li
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shimizu
authors.forename: Meena K
authors.initials: MK
authors.lastname: Sakharkar
authors.forename: Motoo
authors.initials: M
authors.lastname: Utsumi
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Zhang
authors.forename: Norio
authors.initials: N
authors.lastname: Sugiura
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D018441:Biofilms; D017931:DNA Primers; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D008387:Marine Toxins; D052998:Microcystins / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D010461:Peptones / Q000378:metabolism; D016133:Polymerase Chain Reaction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
chemical_list: D017931:DNA Primers; D008387:Marine Toxins; D052998:Microcystins; D009566:Nitrates; D010461:Peptones; D000644:Quaternary Ammonium Compounds; C057862:cyanoginosin LR; D005947:Glucose