title: Expression, secretion and bactericidal activity of type VI secretion system in Vibrio anguillarum.
abstract: The type VI secretion system (T6SS) was recently shown to modulate quorum sensing and the stress response in Vibrio anguillarum serotype O1 strain NB10. It is not known whether there is a functionally active T6SS in other serotypes of V. anguillarum. Here, homologues to T6SS cluster VtsEFGH and hemolysin-coregulated protein (Hcp)-encoding genes were found to be prevalent and conserved in clinical isolates of V. anguillarum from fish, including four O1 and five non-O1 serotype strains. Unexpectedly, only the non-O1 serotype strains expressed VtsEFGH and Hcp under laboratory and marine-like conditions, in contrast to the serotype O1 strains. This suggested that the V. anguillarum non-O1 serotype strains tested have constitutive expression of T6SS. Examination of a representative non-O1 strain, MHK3, showed that Hcp production was growth phase dependent and that maximum Hcp production was observed in the exponential growth phase. Moreover, Hcp production by MHK3 was most active under warm marine-like conditions. Further examination revealed a correlation of the constitutive expression of T6SS with bactericidal activity against Escherichia coli and Edwardsiella tarda. The work presented here suggests that the constitutive expression of T6SS provides V. anguillarum with advantage in microbial competition in marine environments.
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, People's Republic of China.|Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, People's Republic of China.|Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Shu
authors.initials: S
authors.lastname: Yue
authors.affiliation: Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Gui-Yang
authors.initials: GY
authors.lastname: Li
authors.affiliation: Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, People's Republic of China.|Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Xiao-Ran
authors.initials: XR
authors.lastname: Wang
authors.affiliation: Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China.
authors.forename: Shu-Fang
authors.initials: SF
authors.lastname: Li
authors.affiliation: Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, People's Republic of China. mozl@ysfri.ac.cn.
authors.forename: Zhao-Lan
authors.initials: ZL
authors.lastname: Mo
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D020609:Edwardsiella tarda / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005399:Fishes / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D053038:Quorum Sensing / Q000502:physiology*; D000069376:Type VI Secretion Systems / Q000378:metabolism*; D014733:Vibrio / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D000069376:Type VI Secretion Systems
keywords: Bactericidal activity; Hcp; T6SS; Vibrio anguillarum