Effects Of Organophosphate-degradation Bacteriums On Microbials Of Soybean Rhizosphere

Phosphorous is one of the essential macroelements of plants, while the main existingform of phosphorous in soil is insoluble and has low bioavailability. Therefore, the utilizationratio of soil phosphorous was low. Organic-phosphorous is the important component of soilinsoluble phosphorous which usually accounts for20%-50%of the soil total phosphorus.Phytate is the main form in soil organic-phosphorous which accounts for10%-50%of soilorganic-phosphorous. This research aimed to screen strains with high organic-phosphorousdegradating capacity from soil of orchard, vegetable field, grassland and drain outlet ofinsecticide factory. Then chose the bacteria with high degradating ability for the identificationof molecular biology, and soybean pot experiment was conducted to study the impact onsoybean plants and rhizosphere soil microbial. The research results were as follows:1. Screening and growth characteristics study of phosphate-degradating bacterial strainsSolid medium of degradating circle and Mo-Sb Antispetrophotography method was usedon Phytin and lecithin medium to screen bacteria and molecular biological method was usedto identification of bacteria. Judging from degradating circle, the highest D/d value reached5.5was from Z3-6. On lecithin medium, only L5-2D/d value attained2.6was ideal.Secondary screening showed that, phytate medium screened four strains whose degradatingrate were higher. Only the L7-1and L5-2which were selected from lecithin medium hadbetter degradating ability,84.1%and76.7%, respectively.Biochemical characteristics and16S rDNA analysis demonstrated that these6bacteriawere Pseudomonas plecoglossicida, Pseudomonas putida, Pseudomonas fluorescens, Pantoeaagglomerans and Brevibacillus agry.When the temperature keep at28℃, the strains had high degradating ability. The highestdegradating rate of Z2-3appeared when the initial pH was8.5, and Z3-5could keep highdegradating rate when the initial pH were both8.0and8.5. There was little influence of initialpH on Z3-8and Z4-1. L5-2and L7-1solubilizing rate maximum value appeared in theinitial pH=7.5. 2. The influence of organic-phosphorous degradating bacteria on potted soybean growth,soil phosphorus and enzyme activitiesStrain Z2-3could significantly improve the root activity in seed filling stage, then Z4-1and Z3-8made soybean maturity stage root activity increased significantly (p <0.05).Inoculated Z4-1made the chlorophyll content significantly increased in seedling, while Z3-8treatment leaf chlorophyll content significantly lower than the control. Leaf chlorophyllcontent in inoculation treatments were higher than that of control in flowering stage, seedfilling stage and mature, and the treatment inoculated L7-1was significant higher than thecontrol. Then strain Z2-3and Z4-1could significantly improve the the plants totalphosphorus content in the flowering period; both inoculation Z4-1and L7-1couldsignificantly increase total phosphorus of mature plants.The inoculation of Z2-3and Z3-8was able to improve soil available phosphoruscontent in seedling. In maturity period, inoculation Z4-1and L7-1increased soil availablephosphorus content. On T3and T4treatment, soil organic phosphorous were significantlylower than that on control in seedling stage, flowering and seed filling stage, and when inmaturity only T4treatment soil organic phosphorus content was low.The strain Z2-3and Z3-8improved soil invertase activity in flowering stage, while Z4-1improved that of seed filling stage. In maturity, T1(inoculated Z2-3) and T4(inoculatedL7-1) treatments urease activity was significantly lower than that of the control and T3(inoculated Z4-1). With the advent of flowering, T1and T2enzyme activity weresignificantly higher than the control. Alkaline phosphatase activity were significantly higherthan the control in mature processing except T1. Throughout the growth period, soil catalaseactivity on T1were highest, and catalase activity on T2treatment was also significantlyhigher than that of the control in seedling period.3. Effects on soil micro-ecosystem of soybean pot experiment from organic-phosphorousdegradating bacteriaCompared with control, T1and T3treatment significantly increased AWCD value ofseed filling stage and mature. Judging by the soil microbial community diversity index,inoculated Z2-3helped to improve the soybean seedling soil microbial community functionalstructure, L4-1made soil microbial diversity and evenness decreased in seed filling stage.Inoculation changed soil bacteria utility of the six categories carbon source of all periods, and had some impact on the microbial community functional structure. The principal componentanalysis showed that the strains altered the microbial community functional structure to agreat extent.Both Z2-3and L7-1could survive and their abundance kept between3.4%and5.1%.Incubation of the tow strains would impact on abundance of some bacterial in soil, and led toenrichment or reduce of microbial but had on effects on soil microbial community diversityand eveness.