Bacterioplankton Community Structure In Response To Algal Blooms And Applications Of Algal Biomass

Cyanobacterial bloom is a worldwide environmental problem,and its large-scale outbreak will seriously affect the aquatic ecosystem.The bacterioplankton play an important role in the biogeochemical cycle.The study of the succession of the bacterioplankton community structure at different stages of cyanobacterial bloom will help to understand the process of cyanobacterial bloom.During the massive outbreak of cyanobacterial bloom,mechanical salvage is a timely and effective control measure,which has been widely applied in China.After cyanobacteria salvage,algae water is separated and a large amount of algal biomass is produced,which is likely to cause secondary pollution to the environment.Therefore,it is very important to find an effective way of resource utilization for cyanobacteria biomass.On the other hand,the tail water produced by the separation still contains some individual cyanobacterial cells or small algal aggregates,which need further treatment.In view of the above problems,on the basis of ecological investigation and a large number of experimental studies,this paper systematically analyzed the changes of bacterial community structure in the pre,middle and late stages of cyanobacterial bloom,and successfully developed a flocculant for the removal of algae cells in the water after algae water separation,and explored the resource utilization of cyanobacterial biomass.Methods include the application of cyanobacterial biomass derived bioelectrode in bioelectrochemical system and electrochemical detection of riboflavin.The main contents are as follows:1.The characteristics of planktonic community structure in the pre,middle and late stages of algal bloom in a typical eutrophic lake,Chaohu Lake were analyzed by high-throughput sequencing technology.The results showed that the community structure of bacterioplankton changed significantly during the outbreak of algal bloom.The total and more abundant bacterioplankton community showed a similar trend during different blooms,while the changes in the structure of the rare bacteria community were significantly different.During the cyanobacterial bloom,the diversity of bacterioplankton community structure was the lowest.In the late stage of blooms,the total and more abundant bacterioplankton community structure was restored to a certain extent,mainly attributable to the OTUs changes of the phyla Proteobacteria,Bacteroidetes,Actinobacteria and Firmicute.The corresponding environmental factors that caused differences in planktonic bacterial communities were identified by classical correspondence analysis.The corresponding environmental factors that caused differences in bacterioplankton communities were identified by classical correspondence analysis(CCA).2.A novel method for flocculating and settling cyanobacterial cells is proposed.Using Microcystis aeruginosa sa model,hydrolyzed urine as a flocculant,more than 97%of the algae cells can be removed within 6 hours,and the nitrogen and phosphorus nutrients in the urine are reclaimed through struvite formation.The addition of magnesium ions can promote flocculation efficiency,nutrient removal and gain of struvite.Calcium ions can also enhance the removal efficiency of algae cells through the formation of calcium phosphate.No obvious algal cell damage was observed in the flocculation process.3.A low-cost biochar derived from algal biomass via pyrolysis was obtained.Biochar deposited on the surface of ITO glass was used as a biological anode(Biochar/ITO anode).Compared with the ITO electrode,the Biochar/ITO anode exhibits better biocompatibility,lower charge transfer resistance and stronger electrochemical response and adsorption capacity to the redox medium.The MEC with biochar anode showed excellent electricity generation capacity.The maximum current density was 5.4 and 4.1 times higher than that of ITO and graphite plate anode respectively.The riboflavin was modified onto the surface of biochar/C electrode by in situ adsorption.Cyclic voltammetry showed that the modification was successful and riboflavin was not easy to resolve.The riboflavin/biochar/C electrode could be used in the anode of bioelectrochemical system to increase the adhesion of bacteria on the electrode surface and obviously improve the production of biological current.4.A galss carbon(GC)electrode modified with biochar for quantification of riboflavin was prepared.Cyclic voltammetric analysis showed that the electrochemical response intensity of riboflavin on cyanobacteria bioelectrode was pH dependent,and pH 2.16 had the strongest electrochemical response.The differential pulse voltammetry(DPV)is used for quantitative analysis of riboflavin.The detection range is 5 nM?4 ?M and the minimum detection limit is 5 nM.Vitamin,ion and glucose have no obvious interference on riboflavin determination.This method was successfully applied to determine the riboflavin content in food and pharmaceutical.