Research On The Soil Microflora And The Diversity Of PGPR From Mangrove Of Three Places In South China

The relationship between the quantity of soil microbe and the main physic-chemical factors of mangrove soil,as well as the distribution of PGPR from mangrove rhizosphere in Shenzhen,Longhai and Haikou were investigated.The genetic diversity of 26 PGPR isolated from rhizosphere of mangrove forest in South China was evaluated by RFLP analysis of 16S rDNA genes and 16S rDNA sequencing,all PGPR were amplified whether the nifH gene existed or not.Besides,ability of phosphate-dissolving bacteria for dissolution of unsolvable inorganic phosphorus and the media of pH were tested.The conclusion of this study was as follow:The amount of soil bacteria accounted for the majority of the total amount of soil microbe,while the amounts of soil actinomyces and filamentous fungi were in the minority.The quantity of microbes, bacteria,actinomyces and filamentous fungi from Shenzhen mangrove soil is more than the other two places,especially the quantity of filamentous fungi were greater than other two places(P＜0.05).The quantity of microbe and bacteria were highly remarkable positive correlated with total nitrogen and total phosphorus of soil(P＜0.01),the quantity of actinomyces was remarkable positive correlated with total nitrogen and total phosphorus of soil(P＜0.05),and the quantity of fungi was also remarkable positive correlated with total phosphorus of soil (P＜0.05).The multiple regression analysis indicated that total nitrogen and total phosphorus respectively played an important role on impacting the quantities of microbe and bacteria as well as the actinomyces and fungi.24 phosphate-dissolving bacteria and 2 azotobacter were selected from different part of mangrove rhizophere.The quantity of phosphate-dissolving bacteria in soil was more than another two parts of mangrove rhizosphere,and 2 azotobacter were isolated from the surface of root.The dendrogram of 16S rDNA PCR-RFLP revealed the isolates were assembled at 59%similarity level.At the similarity level of 90%,all 26 strains were grouped into 6 subgroups and 7 unattached branch.The identification result of representative strains showed that Vibrio alginolyticus,Vibrio parahaemolyticus,Allomonas enterica,Paenibacillus ginsengagri,Bacillus pumilus,Bacillus megaterium,Klebsiella sp.,Enterobacter intermedius,Uncultured Shigella sp.,Bacillus aquimaris and Pseudomonas mosselii were isolated.Bacillus sp is the dominant species,the result characterized versatile bacterial diversity.The 360bp nifH gene segment were amplified from the azotobacter such as FJN and SZN4,phosphate-dissolving bacteria such as HN1-1,HN1-2,HN1-3,HN011,SZ002,SZ7-1,FJ001,FJ002,FJ008,FJ010 and FJ011.In addition,ability of phosphate-dissolving bacteria for dissolution of unsolvable inorganic phosphorus and the media of pH were tested.All representative strain own the ability of phosphate-dissolving,especially HN012 had a strongest phosphate-dissolving capability.The pH of liquid media of strain both were decreased more or less.