title: Vernalophrys algivore gen. nov., sp. nov. (Rhizaria: Cercozoa: Vampyrellida), a New Algal Predator Isolated from Outdoor Mass Culture of Scenedesmus dimorphus.
abstract: Microbial contamination is the main cause of loss of biomass yield in microalgal cultures, especially under outdoor environmental conditions. Little is known about the identities of microbial contaminants in outdoor mass algal cultures. In this study, a new genus and species of vampyrellid amoeba, Vernalophrys algivore, is described from cultures of Scenedesmus dimorphus in open raceway ponds and outdoor flat-panel photobioreactors. This vampyrellid amoeba was a significant grazer of Scenedesmus and was frequently associated with a very rapid decline in algal numbers. We report on the morphology, subcellular structure, feeding behavior, molecular phylogeny, and life cycle. The new amoeba resembles Leptophrys in the shape of trophozoites and pseudopodia and in the mechanism of feeding (mainly by engulfment). It possesses two distinctive regions in helix E10_1 (nucleotides 117 to 119, CAA) and E23_1 (nucleotides 522 and 523, AG) of the 18S rRNA gene. It did not form a monophyletic group with Leptophrys in molecular phylogenetic trees. We establish a new genus, Vernalophrys, with the type species Vernalophrys algivore. The occurrence, impact of the amoeba on mass culture of S. dimorphus, and means to reduce vampyrellid amoeba contamination in Scenedesmus cultures are addressed. The information obtained from this study will be useful for developing an early warning system and control measures for preventing or treating this contaminant in microalgal mass cultures.
authors.affiliation: Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China Laboratory for Algae Research and Biotechnology, College of Technology and Innovation, Arizona State University, Mesa, Arizona, USA springgong@ihb.ac.cn huqiang@ihb.ac.cn.
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Gong
authors.affiliation: School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Patterson
authors.affiliation: College of Life Sciences and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yunguang
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
authors.forename: Zixuan
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Laboratory for Algae Research and Biotechnology, College of Technology and Innovation, Arizona State University, Mesa, Arizona, USA.
authors.forename: Milton
authors.initials: M
authors.lastname: Sommerfeld
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China Laboratory for Algae Research and Biotechnology, College of Technology and Innovation, Arizona State University, Mesa, Arizona, USA springgong@ihb.ac.cn huqiang@ihb.ac.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Hu
mesh_terms: D056907:Cercozoa / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology / Q000648:ultrastructure; D016054:DNA, Protozoan / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D058086:Microalgae / Q000254:growth & development / Q000469:parasitology*; D046529:Microscopy, Electron, Transmission; D058433:Photobioreactors / Q000469:parasitology*; D010802:Phylogeny; D061005:Ponds / Q000469:parasitology*; D011554:Pseudopodia / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D044444:Scenedesmus / Q000254:growth & development / Q000469:parasitology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D053058:Trophozoites / Q000648:ultrastructure
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal
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