| In order to study the phosphorus dissolving mechanism of marine phosphorus-dissolving bacteria,enrich the research of marine phosphorus-dissolving bacteria,and further study the correlation between environmental factors and marine phosphorus-dissolving bacteria.In this paper,the effect of temperature on the expression of phoD gene in phosphorus-solubilizing bacteria was studied,and the difference of phoD gene expression in phosphorus-solubilizing bacteria under the influence of environmental factors was deduced,so as to explore the relationship between environmental factors and the expression of phosphorus-solubilizing bacteria and environmental adaptability.At the same time,high-throughput technology was used to study the diversity of bacterial flora and gene diversity of phosphorus-soluble bacteria in surface sediments of the Yangtze Estuary,and the correlation between environmental factors such as pH,oxygen,temperature and phosphorus concentration and the diversity of bacterial flora and gene diversity of phosphorus-soluble bacteria was analyzed.The main research contents and results are as following:1.In order to investigate the changes of microbial community structure and diversity in surface sediments of the Yangtze Estuary and the correlation between microbial population distribution and environmental factors in this region,the community structure and diversity of surface sediments of the Yangtze Estuary in summer were studied based on high-throughput sequencing technology of 16 S rRNA gene.The population distribution and diversity of microorganisms at Sampling Pointsat were studied with respect to temperature,pH value,DO concentration and organic phosphorus concentration.Redundancy analysis was carried out for environmental factors of degree and inorganic phosphorus concentration.From the results of community composition,we can see that Proteobacteria was higher in the sediments of the Yangtze Estuary,followed by Acidobacteria and Actinobacteria.Proteobacteria has the highest relative abundance in A5-5 and the lowest relative abundance in A6-3.At the class level,the dominant microorganisms are Gamma Proteobacteria and Delta Proteobacteria.Gamma Proteobacteria ranked first in relative abundance,and was thehighest in surface sediments of A3-8 Yangtze Estuary,with relative abundance of14.9%-24.9% in other sampling sites.The relative abundance of Delta Proteobacteria was 19.5%,the highest in surface sediments of A2-3 Yangtze Estuary,and 9.5%-24.2%in other sampling sites.At the subordinate level,Woeseia is dominant in sediments,with the highest relative abundance in A3-8 and the lowest relative abundance in C2(1.0%)and the remaining stations(3.4%-11.6%).Redundancy analysis showed that A4-5,A5-4,D3,A2-5,E3,B1 distributed in the first quadrant,mainly related to IP concentration;A6-7,A6-6,A2-4,A1-3,C2,A6-3,A2-6,A3-8,E3 distributed in the left side of the first ordination axis,where A6-7,A6-6 distributed in the second quadrant,and A2-4,A1-3,C2,A6-3,A2-6,A3-8 distributed in the third quadrant,all related to pH and DO concentration.F2,H2,G1,A2-3 distributes in the fourth quadrant and is mainly related to OP concentration and temperature.The structure and diversity of microbial communities in surface sediments of the Yangtze Estuary are affected by many environmental factors,showing a complex distribution trend,which is conducive to grasping the distribution and relative abundance of microorganisms in surface sediments of the Yangtze Estuary,and providing a reference for further study of marine ecological environment.2.Alkaline phosphatase is the most important organophosphorus hydrolase,which can dephosphorylate the organic matter,remove the phosphate group on the substrate molecule by hydrolyzing the phosphate ester,and produce orthophosphate.Therefore,the study of alkaline phosphatase gene diversity is conducive to revealing microbial groups that have important influence on the degradation of organic phosphorus.Based on 16 S rRNA gene high-throughput sequencing technology,the phoD alkaline phosphatase gene diversity of surface sediment microorganisms in the Yangtze Estuary in summer was studied.The environmental factors of phoD alkaline phosphatase diversity and temperature,pH value,dissolved oxygen concentration,organic phosphorus concentration and inorganic phosphorus concentration were redundantly analyzed.The results showed that the phoD alkaline phosphatase gene mainly came from Cupriavidus and Collimonas,while the alkaline phosphatase gene of Cupriavidus was the highest in the library,accounting for 40.8% of the library.The diversity of G1 stations is higher than that of other stations.The results show that the phoD alkaline phosphatase genes of surface sediment microorganisms in the Yangtze Estuary are highly diverse,and the alkaline phosphatase coded by these genes may play an important role in phosphorus transformation in surface sediments of the YangtzeEstuary.Redundancy analysis(RDA)results showed that the concentration of pH and DO was positively correlated,and the concentration of organic phosphorus was positively correlated with temperature.The diversity of microbial communities in the Yangtze Estuary is affected by many environmental factors,showing a complex distribution trend and correlation.A5-5,B1,A5-4 and E3 were distributed in the first quadrant,mainly related to IP concentration.A4-5,A6-7,C2,A6-3,A1-3,A3-8,A2-4,A2-6 are distributed on the left side of the first ordination axis.Among them,A4-5,A6-7 and C2 are distributed in the second quadrant,and A2-4,A1-3,C2,A6-3,A2-6and A3-8 are distributed in the third quadrant,which are all related to the concentration of PH and DO.H2,A2-3,F2 and G1 distribute in the fourth quadrant,mainly related to OP concentration and temperature.Among them,A6-6,A2-5 and D3 were located near the intersection of the two ordination axes,indicating that microorganisms containing phoD alkaline phosphatase gene were prevalent during the survey.The phoD alkaline phosphatase genes of surface sediment microorganisms in the Yangtze Estuary are highly diverse,and the alkaline phosphatase coded by these genes may play an important role in phosphorus transformation in surface sediments of the Yangtze Estuary.Redundancy analysis(RDA)showed that environmental factors were important factors affecting the structure and diversity of microbial community containing phoD alkaline phosphatase in sediments from different stations in the Yangtze Estuary.Therefore,monitoring environmental factors in the Yangtze Estuary is helpful to grasp the community structure of phosphorus-soluble microorganisms in the Yangtze Estuary,and to provide reference for further study of phosphorus transformation cycle in the marine environment.3.In this paper,the surface sediments of the Yangtze Estuary were deposited on a lecithin plate according to the presence of phosphorus-soluble rings around the bacteria.172 strains of organophosphorus bacteria were isolated from the samples.Through 16 S rRNA gene sequencing and phylogenetic analysis,they belonged to 8genera.Vibrio was the most abundant genus,followed by Bacillus.DNA Star software was used to sequence 26 different kinds of organophosphorus bacteria.Vibrio was the most species,followed by Bacillus.This indicates that there are abundant population diversity of organophosphorus bacteria in the surface sediments of the Yangtze Estuary,and they play an important role in the transformation cycle of organophosphorus bacteria in the Yangtze Estuary waters.4.Using YCWA18 as the experimental strain,16 S as the internal reference gene and phoD as the target gene,the expression of phoD-related genes was detected byfluorescence quantitative PCR at different growth temperatures.The difference of gene expression was calculated by ??Ct method.The results showed that the highest expression of phoD gene was found at 20?,followed by the highest expression at37?,suggesting that the phosphorus-solubilizing bacteria in the marine environment had strong phosphorus-solubilizing ability at 20?. |
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