The Reaserch Of Isolation And Identification Of High Lipid Potential Monoraphidium Sp. And Their Symbiotic Bacteria

Biodiesel has gained more and more attention as an alternative energy source because of the increasing oil prices and climate change concerns.Due to their high oil content and rapid biomass production,microalgae have long been recognized as potentially good source for biofuel production.The most important decisions in obtaining oil from microalgae are the choice of algal species and the explore of their growth condition including associated bacteria living with.In this study,The potential of four microalgae strains for biodiesel production were isolated from three plateau freshwater lakes in Yunnan Province.79 green algal strains were isolated and identificated four high lipid Monoraphidium sp.by morphological and 18s rRNA sequence analysis.Albeit the same genus they are,difference in their morphology and 18S rRNA sequence can be found and thus they were named Monoraphidium sp.FXY-10,Monoraphidium sp.QLZ-3,Monoraphidium sp.QLY-1 and Monoraphidium sp.YLY-2,respectively.The growth rate,biomass productivity,lipid productivities,and fatty acid profiles of FXY-10 and QLY-1 were investigated and compared under autotrophic and heterotrophic conditions.QLZ-3 and YLY-2 were not growth under heterotrophic condition.FXY-10 and QLY-1 reached higher lipid content(56.8%and 52.79%)under autotrophic condition than those(37.56%and 27.07%)under heterotrophic condition.QLZ-3 reached a higher biomass(1.595gL-1)with the lowest lipid content(23.8%).However,FXY-10 and QLY-1 had higher lipid productivity(138.42mgL-1d-1 and 56.24 mgL-1d-1)under heterotrophic condition.Moreover,Saturated and monounsaturated fatty acids of FXY-10 reached 76.7%,higher C16-C18(85.3%)under heterotrophic culture.Therefore,Monoraphidium sp.FXY-10 can be the best candidate for biodiesel production.Meanwhile,different kinds of symbiotic bacteria were observed and isolated from different strains,with their specific growth rate(?)and the ability of lipid production varied from each other under autotrophic condition,via the 16S rRNA sequence analysis.According to the diversity of associated bacteria can be discovered in microalgal culture obviously,the interaction between bacteria and microalgal strains growth will also be discussed in this study.