Protoplast Fusion And Mutation Breeding Of Two Microalgae

Two microalgae were screened from the wastewater with treatment project of shijiazhuang city and hebei province,one is Scenedesmus?HT-1?with the properties of oil production;another is Chlorella?HC-2?with the removal of total nitrogen and total phosphorus.As is known to all,the good algae species can be selected by protoplast fusion and mutagenesis.Therefore,the method of protoplast fusion of microalgae was explored in thesis,the protoplast fusion of oil-producing microalgae and wastewater treatment microalgae was screened out in order to obtain a microalgae with strong wastewater treatment capacity and high lipid production rate;furthermore,the preliminary study on ultraviolet mutagenesis of Chlorella was carried out to obtain algae strains with excellent wastewater treatment performance or oil production performance,which laid a foundation for the comprehensive utilization of microalgae.The conditions of enzymatic hydrolysis of Chlorella microalgae and Scenedesmus microalgae were selected,and the conditions of protoplasmic preparation and fusion were determined:4%hemicellulase and 2%collapse enzyme 500?L,enzymolysis temperature30?,enzymolysis time 4h,150r/min shake incubation chlorella processing;1%cellulase,hemicellulase and segregation enzyme 400?L,enzymolysis temperature 25?,enzymolysis time 4h,150r/min shaking handle scenedesmus incubation.Then the protoplast was fused by PEG6000.The plasmplasm preparation rate of Chlorella microalgae and Scenedesmus microalgae was 44.44%and 61.11%,respectively;and the regeneration rate was 49.85%and40.17%.Secondly,the activity of protoplast was determined by Evans land method.Then,0.2mol/L of KCl and 0.1%of CaCl₂ were added into the ordinary BG-11 medium as the regeneration medium of protoplast.Subsequently,one fusion strain was successfully screened with a lipid content of 13.89%,and the removal rates of total nitrogen and total phosphorus were 53.54%and 60.24%.In the end,the UV light source of 38W,the distance of the light source of 36-40cm and the irradiation time of 25min were selected to induce chlorella micrococcus.Three strains of microalgae were screened,which were UHC-2 and UHC-7 with good stability and oil content of 10.41%and 10.77%and UHC-5 with removal rate of total nitrogen,total phosphorus and COD in the wastewater reaching 51.28%,58.77%and 45.19%.