title: Synergistic algicidal effect and mechanism of two diketopiperazines produced by Chryseobacterium sp. strain GLY-1106 on the harmful bloom-forming Microcystis aeruginosa.
abstract: A potent algicidal bacterium isolated from Lake Taihu, Chryseobacterium sp. strain GLY-1106, produces two algicidal compounds: 1106-A (cyclo(4-OH-Pro-Leu)) and 1106-B (cyclo(Pro-Leu)). Both diketopiperazines showed strong algicidal activities against Microcystis aeruginosa, the dominant bloom-forming cyanobacterium in Lake Taihu. Interestingly, these two algicidal compounds functioned synergistically. Compared with individual treatment, combined treatment with cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) significantly enhanced algicidal activity, accelerated the increase in intracellular reactive oxygen species (ROS) levels in M. aeruginosa, and further decreased the activities of antioxidases, effective quantum yield and maximal electron transport rate of M. aeruginosa. The results also showed that the algicidal characteristics of cyclo(4-OH-Pro-Leu) are distinct from those of cyclo(Pro-Leu). Cyclo(4-OH-Pro-Leu) mainly interrupted the flux of electron transport in the cyanobacterial photosynthetic system, whereas cyclo(Pro-Leu) mainly inhibited the activity of cyanobacterial intracellular antioxidases. A possible algicidal mechanism for the synergism between cyclo(4-OH-Pro-Leu) and cyclo(Pro-Leu) is proposed, which is in accordance with their distinct algicidal characteristics in individual and combined treatment. These findings suggest that synergism between algicidal compounds might be used as an effective strategy for the future control of Microcystis blooms.
authors.affiliation: State Key Laboratory of Microbial metabolism, and School of Life Science &Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.
authors.forename: Xingliang
authors.initials: X
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Microbial metabolism, and School of Life Science &Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.
authors.forename: Xianglong
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial metabolism, and School of Life Science &Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.
authors.forename: Jianliang
authors.initials: J
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Microbial metabolism, and School of Life Science &Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000898:Antibiosis; D018533:Biomass; D045247:Chryseobacterium / Q000502:physiology*; D054659:Diketopiperazines / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D057097:Harmful Algal Bloom / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D046931:Microcystis / Q000187:drug effects* / Q000502:physiology*; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D054659:Diketopiperazines; D010456:Peptides, Cyclic; D017382:Reactive Oxygen Species