title: Lysing activity of an indigenous algicidal bacterium Aeromonas sp. against Microcystis spp. isolated from Lake Taihu.
abstract: This study aimed to isolate and characterize an indigenous algicidal bacterium named LTH-1 and its algae-lysing compounds active against three Microcystis aeruginosa strains (toxic TH1, nontoxic TH2 and standard FACHB 905). The LTH-1 isolated from Lake Taihu, near Wuxi City in China, was identified as Aeromonas sp. based on its morphological characteristic features and phylogenetic analysis by sequencing of 16S rDNA. Extracellular compounds produced by LTH-1 showed strong algaelysing activity, and they were water-soluble and heat-tolerant, with a molecular mass lower than 2 kDa. Two algae-lysing compounds were isolated and purified from extracellular filtrate using silica gel column chromatography. One of these was identified as phenylalanine (C9H11NO2, m/z 166.0862) and the other (C8H16N2O3, m/z 189.1232) was unidentified by hybrid ion trap/time-of-flight mass spectrometry coupled with a high-performance liquid chromatography (LC/MS-IT-TOF) system. The half maximal effective concentration (EC50) of phenylalanine produced by LTH-1 against FACHB 905 was 68.2 +/- 8.2 microg mL(-1) in 48h. These results suggest that the algicidal Aeromonas sp. LTH-1 could play a role in controlling Microcystis blooms, and its extracellular compounds are also potentially useful for regulating blooms of the harmful M. aeruginosa.
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University Nanjing, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Li
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Li
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wei
authors.forename: Guang
authors.initials: G
authors.lastname: Yu
authors.forename: Lihong
authors.initials: L
authors.lastname: Yin
authors.forename: Geyu
authors.initials: G
authors.lastname: Liang
authors.forename: Yuepu
authors.initials: Y
authors.lastname: Pu
mesh_terms: D000333:Aeromonas / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D000898:Antibiosis / Q000502:physiology*; D002681:China; D004269:DNA, Bacterial / Q000032:analysis; D060106:Lakes / Q000382:microbiology*; D050296:Microbial Viability; D046931:Microcystis / Q000502:physiology*; D008969:Molecular Sequence Data; D010649:Phenylalanine / Q000737:chemistry; D010802:Phylogeny
chemical_list: D004269:DNA, Bacterial; D010649:Phenylalanine