Spatiotemporal Distribution Of Virioplankton And Isolation And Screening Of Lytic Phages In Yuncheng Salt Lake

Planktonic viruses are the general term for all types of viruses suspended in water environments.They may be the second largest group of organisms on the earth after prokaryotes.They play an important role in driving the biochemical cycle of the earth and regulating global climate change.Planktonic viruses can affect the flow of carbon and nutrients in the microeating ring,and promote gene exchange and conversion between microbial groups by infecting the host,thereby regulating the population structure and community succession of microorganisms,and regulating aquatic microorganisms at the genetic level Community structure.Therefore,research on the resources of planktonic viruses in nature not only helps to reveal their functions and positioning in the water environment and even the entire ecosystem,but also provides scientific basis for the monitoring,protection and management of the water environment.This project takes the plankton virus resources in Yuncheng Salt Lake as the research object,and carries out related researches on the temporal and spatial distribution of salt lake plankton viruses,the separation and screening of specific phages and their biological characteristics.The main research content and results are as follows.Sampling points are planned for the Yuncheng Salt Lake,20 of them are selected for monthly sampling,the plankton virus is counted by fluorescence microscopy,the abundance of plankton bacteria is analyzed by the dilution coating plate method,and the chlorophyll in the salt lake water body is analyzed,Nitrogen,phosphorus,p H,salinity,temperature and other related environmental factors were detected,and SPSS 8.2 software was used to comprehensively analyze the abundance of salt lake plankton viruses and their correlation with the host and environmental factors,and transmission electron microscopy was used to observe the morphology of floating viruses in salt lake water samples.The results showed that the changes in the abundance of planktonic viruses were positively correlated with bacterial content,and positively correlated with temperature,but there was no correlation with other environmental factors in the water body.Bacteria content is positively correlated with temperature.Phosphorus content is negatively correlated with p H and temperature,but has a significant positive correlation with salinity.There is a negative correlation between p H and salinity.The morphology of the phytoplankton virus mainly includes microspherical,short rod-shaped,long rod-shaped,filamentous,tadpole-shaped,etc.,among which the microspherical viruses are the dominant ones,and the particle diameter is 20-80 nm.Using the double-layer plate method,a cleavage phage that can be infected with the halophilic bacterium Chromohalobacter sp.LY7-4 was isolated from the Yuncheng Salt Lake and named CJL-8.The method of PEG precipitation and Sefinose TM 4B gel filtration chromatography was used to concentrate and purify the bacteriophage CJL-8,and its morphological characteristics,nucleic acid type,protein composition and biological characteristics were studied.The results showed that the bacteriophage CJL-8 showed the characteristics of a typical long-tailed bacteriophage.The head is a regular polyhedron and has a stereosymmetric structure with a diameter of about 75 nm and a thick and long tail(145nm×12 nm).The phage genome is double-stranded DNA.Restriction analysis showed that the phage DNA could not be cut.It is speculated that the relevant restriction site was modified by methylation.The capsid of bacteriophage CJL-8 contains three main structural proteins with molecular weights of 55.8 k Da,46.0 k Da and 35.9 k Da,respectively.The phage has a wide host range and is more sensitive to chloroform,indicating that its structure does not contain a lipid envelope.Under low-salt conditions,the phage titer is zero after 30 min,indicating that CJL-8 is a halophilic phage.The best activity condition of CJL-8 is temperature 40? and p H5.0.The research results of this subject can provide data reference for the overall study of the salt lake and have important significance for revealing the distribution,function and positioning of the plankton virus in the special ecosystem of the salt lake.