title: Novel insights into the algicidal bacterium DH77-1 killing the toxic dinoflagellate Alexandrium tamarense.
abstract: Algicidal bacteria may play a major role in controlling harmful algal blooms (HABs) dynamics. Bacterium DH77-1 was isolated with high algicidal activity against the toxic dinoflagellate Alexandrium tamarense and identified as Joostella sp. DH77-1. The results showed that DH77-1 exhibited algicidal activity through indirect attack, which excreted active substance into the filtrate. It had a relatively wide host range and the active substance of DH77-1 was relatively stable since temperature, pH and storage condition had no obvious effect on the algicidal activity. The algicidal compound from bacterium DH77-1 was isolated based on activity-guided bioassay and the molecular weight was determined to be 125.88 by MALDI-TOF mass spectrometer, however further identification via nuclear magnetic resonance (NMR) spectra is ongoing. The physiological responses of algal cells after exposure to the DH77-1 algicidal substances were as follows: the antioxidant system of A. tamarense responded positively in self-defense; total protein content decreased significantly as did the photosynthetic pigment content; superoxide dismutase, peroxidase enzyme and malondialdehyde content increased extraordinarily and algal cell nucleic acid leaked seriously ultimately inducing cell death. Furthermore, DH77-1 is the first record of a Joostella sp. bacterium being algicidal to the harmful dinoflagellate A. tamarense, and the bacterial culture and the active compounds might be potentially used as a bio-agent for controlling harmful algal blooms.
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; State Key Laboratory of Marine Environmental Science and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China. Electronic address: xryang@iue.ac.cn.
authors.forename: Xiaoru
authors.initials: X
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Marine Environmental Science and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China; Tangdu Hospital, The Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Marine Environmental Science and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Marine Environmental Science and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Changping
authors.initials: C
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Marine Environmental Science and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China. Electronic address: wshwzh@xmu.edu.cn.
authors.forename: Tianling
authors.initials: T
authors.lastname: Zheng
mesh_terms: D001419:Bacteria; D004141:Dinoflagellida / Q000502:physiology*; D004202:Disinfectants / Q000633:toxicity*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D057097:Harmful Algal Bloom; D008315:Malondialdehyde / Q000378:metabolism; D010572:Pest Control, Biological / Q000379:methods*; D013482:Superoxide Dismutase / Q000378:metabolism; D014871:Water Microbiology; D014876:Water Pollution
chemical_list: D004202:Disinfectants; D008315:Malondialdehyde; D013482:Superoxide Dismutase
keywords: Algicidal bacteria; Algicidal mechanism; Algicidal substance; HABs control; Toxic Alexandrium tamarense