title: Interactions between Scenedesmus and Microcystis may be used to clarify the role of secondary metabolites.
abstract: Microcystis sp. are major players in the global intensification of toxic cyanobacterial blooms endangering the water quality of freshwater bodies. A novel green alga identified as Scenedesmus sp., designated strain huji (hereafter S. huji), was isolated from water samples containing toxic Microcystis sp. withdrawn from Lake Kinneret (Sea of Galilee), Israel, suggesting that it produces secondary metabolites that help it withstand the Microcystis toxins. Competition experiments suggested complex interaction between these two organisms and use of spent cell-free media from S. huji caused severe cell lysis in various Microcystis strains. We have isolated active metabolites from the spent S. huji medium. Application of the concentrated allelochemicals interfered with the functionality and perhaps the integrity of the Microcystis cell membrane, as indicated by the rapid effect on the photosynthetic variable fluorescence and leakage of phycobilins and ions. Although some activity was observed towards various bacteria, it did not alter growth of eukaryotic organisms such as the green alga Chlamydomonas reinhardtii.
authors.affiliation: Department of Plant and Environmental Sciences, Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Harel
authors.forename: Gad
authors.initials: G
authors.lastname: Weiss
authors.forename: Judy
authors.initials: J
authors.lastname: Lieman-Hurwitz
authors.forename: Jenny
authors.initials: J
authors.lastname: Gun
authors.forename: Ovadia
authors.initials: O
authors.lastname: Lev
authors.forename: Mario
authors.initials: M
authors.lastname: Lebendiker
authors.forename: Violeta
authors.initials: V
authors.lastname: Temper
authors.forename: Colin
authors.initials: C
authors.lastname: Block
authors.forename: Assaf
authors.initials: A
authors.lastname: Sukenik
authors.forename: Tamar
authors.initials: T
authors.lastname: Zohary
authors.forename: Sergei
authors.initials: S
authors.lastname: Braun
authors.forename: Shmuel
authors.initials: S
authors.lastname: Carmeli
authors.forename: Aaron
authors.initials: A
authors.lastname: Kaplan
mesh_terms: D064089:Allelopathy; D018744:DNA, Plant / Q000235:genetics; D005618:Fresh Water / Q000382:microbiology; D054884:Host-Pathogen Interactions; D007557:Israel; D046931:Microcystis / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D010788:Photosynthesis; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D044444:Scenedesmus / Q000378:metabolism*; D014118:Toxins, Biological
chemical_list: D018744:DNA, Plant; D012337:RNA, Ribosomal, 18S; D014118:Toxins, Biological