Study On The Allelopathy Of Microcystis Aeruginosa To Chlorella

The frequency and intensity of cyanobacterial blooms are increasing worldwide with major societal and economic costs.Interactions between toxic cyanobacteria and eukaryotic algal competitors can affect toxic bloom formation,but the exact mechanisms of interspecies interactions have remained unknown.Here,we disentangle the complex molecular network of interactions forming the basis for Microcystis aeruginosa negative allelopathic interactions on one green algal competitor,Chlorella vulgaris.We cultivated both species separated by a dialysis membrane in the laboratory and analyzed the effect each species has on each other on the algal proteome and metabolome as well as with biochemical analysis of the signaling molecules involved.We document a novel interspecies molecular network in which M.aeruginosa inhibits growth of C.vulgaris via the release of linoleic acid.The presence of the new inter-species regulatory network between Microcystis and eukaryotic algae was further explored in Lake Taihu(China).Taihu(“large lake” in Mandarin),the third largest freshwater lake in China,is located in Jiangsu province,one of the most densely populated and rapidly growing regions of China.Rapid urbanization and agricultural expansion in the Taihu basin have increased nutrient inputs from wastewater discharge,industries,and chemical fertilizer use.These increases have transformed this once diatom-dominated meso-oligotrophic lake in the 1960 s into a eutrophic,cyanobacteria-dominated system,with toxicMicrocystis spp.blooms now occurring regularly from spring to late fall throughout the lake.These blooms have caused serious environmental,economic,and societal problems,including unsafe water resources for the local population and reduced fisheries and tourism.Phytoplankton communities in Lake Taihu are dominated by cyanobacteria,responsible for approximately 70 % of prokaryotic community(with 30 % of Microcystis aeruginosa),while eukaryotic algae(or eukaryotic aquatic microbe)decreased to low level after algal bloom occurred.Allelopathic compounds(LA)and changes in microbial community structure were studied during a Microcystis bloom.The present study highlights the importance of interspecies cross-talk and allelopathic interactions between a toxic cyanobacterium and one of its algal competitor in bloom dynamics.