title: A freshwater bacterial strain, Shewanella sp. Lzh-2, isolated from Lake Taihu and its two algicidal active substances, hexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 2, 3-indolinedione.
abstract: Cyanobacterial blooms have become a serious problem in Lake Taihu during the last 20 years, and Microcystis aeruginosa and Synechococcus sp. are the two dominant species in cyanobacterial blooms of Lake Taihu. A freshwater bacterial strain, Shewanella sp. Lzh-2, with strong algicidal properties against harmful cyanobacteria was isolated from Lake Taihu. Two substances with algicidal activity secreted extracellularly by Shewanella sp. Lzh-2, S-2A and S-2B, were purified from the bacterial culture of strain Lzh-2 using ethyl acetate extraction, column chromatography, and high performance liquid chromatography (HPLC) in turn. The substances S-2A and S-2B were identified as hexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 2, 3-indolinedione (isatin), respectively, based on liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), and hydrogen-nuclear magnetic resonance (H-NMR) analyses, making this the first report of their algicidal activity toward cyanobacteria. S-2A (hexahydropyrrolo[1,2-a]pyrazine-1,4-dione) had no algicidal effects against Synechococcus sp. BN60, but had a high level of algicidal activity against M. aeruginosa 9110. The LD50 value of S-2A against M. aeruginosa 9110 was 5.7 μg/ml. S-2B (2, 3-indolinedione) showed a potent algicidal effect against both M. aeruginosa 9110 and Synechococcus sp. BN60, and the LD50 value of S-2B against M. aeruginosa 9110 and Synechococcus sp. BN60 was 12.5 and 34.2 μg/ml, respectively. Obvious morphological changes in M. aeruginosa 9110 and Synechococcus sp. BN60 were observed after they were exposed to S-2A (or S-2B) for 24 h. Approximately, the algicidal activity, the concentration of S-2A and S-2B, and the cell density of Lzh-2 were positively related to each other during the cocultivation process. Overall, these findings increase our knowledge about algicidal substances secreted by algicidal bacteria and indicate that strain Lzh-2 and its two algicidal substances have the potential for use as a bio-agent in controlling cyanobacterial blooms in Lake Taihu.
authors.affiliation: State Key Laboratory of Microbial metabolism, School of Life Science and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
authors.forename: Zhenghua
authors.initials: Z
authors.lastname: Li
authors.forename: Shengqin
authors.initials: S
authors.lastname: Lin
authors.forename: Xianglong
authors.initials: X
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Tan
authors.forename: Jianliang
authors.initials: J
authors.lastname: Pan
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002853:Chromatography, Liquid; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007211:Indoles / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D060106:Lakes / Q000382:microbiology*; D007928:Lethal Dose 50; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D046931:Microcystis / Q000187:drug effects; D008853:Microscopy; D008969:Molecular Sequence Data; D011719:Pyrazines / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D020592:Shewanella / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D046940:Synechococcus / Q000187:drug effects
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007211:Indoles; D011719:Pyrazines; D012336:RNA, Ribosomal, 16S; C456900:indolin-2-one