N-fixing, P-solubilizing And Disease-resisting Abilities Of Bacterial Mixtures And Effect Of Cultivation Conditions

With the development of sustainable agriculture and the requirement of food safety, it is important for plant production and utilization to improve the research of microbial-agent. Based on the achieved stable bacterial mixture, we studied the effect of N-fixing, P-solubilizing and function expression in different culture condition, the synergism phenomenon of different strains in the bacterial mixture, and analyzed the physicochemical property of resisting-substance. The results are as follows:1) Determination of N-fixing and P-solubilizing ability of 10 bacterial mixtures, it can be found C15, which can resist Verticillium dahlias Kleb. et. al, have a high nitrogenase activity to 67.0 nmolC2H4.h~-.mg-1Pr, and tricalcium phosphate discomposing to 19.9 mg P.mg-1Pr, and lecithin hydrolyzing ability to 9.1 mg P'mg"'Pr. All others mixtures can solubilize tricalcium phosphate and hydrolyze to lecithin and C15 is best for tricalcium phosphate, C7 is best for lecithin.2) Except for C7, A5, B1, C5 and C7 have a synergistical action to resist Pseudomonas solanaceaxum Smith, and A3, A5, B5, C7 and C15 to Erwinia carotovora subsp.carofovora.3) It can increase bacterial count and ability of disease resist to glucose as carbon source and urea as nitrogen for C7, soluble starch and NH4NO3 for C15. C7 and C15 can be culture in pH 6 to 9 medium and increase bacterial count to one order of magnitude. It is significant difference to P-solubilizing that C7 and C15 be culture in different carbon source. Glucose increase lecithin hydrolyzing ability and lactose increase tricalcium phosphate.4) There is a improvement to assay bacterial P-solubilizing ability. This is, collect cell from culture medium and detach lecithin by ether, tricalcium phosphate by dilute hydrochloric acid, then digesting bacterial cell and assay P of cell. The content is including in P-solubilizing.5) The activity of disease resisting substance of C7 can be keep in pH 2~9, 30℃~90℃ in half hour. The substance can be depose and concentrate by sulphate of ammonia.