Gong Yingchun, Patterson David J, Li Yunguang, Hu Zixuan, Sommerfeld Milton, Chen Yongsheng, Hu Qiang
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
School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia.
Appl Environ Microbiol. 2015 Jun 15;81(12):3900-13. doi: 10.1128/AEM.00160-15. Epub 2015 Mar 27.
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.
微生物污染是微藻培养中生物量产量损失的主要原因，尤其是在室外环境条件下。对于室外大规模藻类培养中微生物污染物的种类知之甚少。在本研究中，从开放式跑道池塘和室外平板光生物反应器中的双形栅藻培养物中描述了一种新的吸血鬼变形虫属和物种，即食藻春变形虫。这种吸血鬼变形虫是双形栅藻的重要捕食者，并且经常与藻类数量的急剧下降有关。我们报告了其形态、亚细胞结构、摄食行为、分子系统发育和生命周期。这种新变形虫在滋养体和伪足的形状以及摄食机制（主要通过吞噬）方面类似于薄变形虫。它在18S rRNA基因的螺旋E10_1（核苷酸117至119，CAA）和E23_1（核苷酸522和523，AG）中有两个独特区域。在分子系统发育树中，它没有与薄变形虫形成单系类群。我们建立了一个新属，即春变形虫属，模式种为食藻春变形虫。文中还讨论了该变形虫的发生情况、对双形栅藻大规模培养的影响以及减少栅藻培养中吸血鬼变形虫污染的方法。从本研究中获得的信息将有助于开发一种早期预警系统和控制措施，以预防或处理微藻大规模培养中的这种污染物。
