| Biological fertilizer is characterized by high efficiency, low cost, innocuity and economization of energy, which may make up for the limitations and disadvantages of chemical fertilizer. The critical problem of developing and utilizating microbial fertilizer is to isolate and screen bacterial strains with high efficient nitrogen fixation, phosphate solubilizing and dissolve resistant kalium. These bacterial strains can supply nutrients elements and microelements for plant growth during the physiological metabolism of these microorganisms.Eighteen bacterial strains were isolated with the function of desolving phosphorus or releasing potassium or fixing nitrogen from different sorts of soil samples in campus of Huazhong Agriculture University. The representative strains of them were designated as PJ07, P01, HZ03, and NY03. Of all the phosphate solubilizing bacteria the strain PJ07 performed the best. Molybdenum-antimony ultraviolet colorimetry tests showed that the soluble phosphorus in minimum media with only phosphorite powder inoculated by PJ07 was 4.7 mg/kg, which was 95.8% higher than control. The result of pot of Glycine max test showed that PJ07 ranked the first and was 43.7% higher than control after statistical analysis. In the test of atomy absorb to mensurate soluble potassium all the strains were respectively 55.9 mg/kg, 45.6 mg/kg, 43.3 mg/kg, 42 mg/kg, 38.8 mg/kg, which were 160%, 93.8%, 41.9%, 39.4 and 34.6% higher than control. HZ03 ranked the first, and then KCAC. In the test of gas chromatogram to mensurate enzyme activity of nitrogen fixation the value of strain NY03 was the highest, which reached to 0.43/amolC2H4/mLX h.Pure bacterial culture and identification showed that the strain PJ07 attributed to Pseudomonas, the strain P01 was Bacillus megaterium, the stain HZ03 was Bacillus mucilaginosus and the stain NY03 Azotobacter chrococcum.The four bacterial stains were also determined by their growth curve, optimized carbon nutrition, optimized nitrogen nutrition, optimized ratio of C/N, optimized early phase pH, and optimized inoculation dosage. The result were as followed. The strain PJ07's logarithmic phage was in time from 6th hours to 30th hours. Its optimized carbon and nitrogen nutrition were glucose and NRtCl respectively. Its ratio of C/N 20~25 and its optimal inoculation dosage 6%. The logarithmic phage of trains P01 and NY03 9h~27h, optimized carbon nutrition amylum and sucrose respectively, optimized nitrogen nutrition NRtNOs, C/N 20, inoculation dosage 3%. The logarithmic phage of trains HZ03 15 h~27 h, optimized carbon and nitrogen nutrition amylum and NH4C1 respectively, C/N 25, inoculation dosage 6%. The optimized pH in early phase of their growth were all 7. All these strainsgrew well in substrate made of bran and chaff and the amount of each bacterial strains reached 1010/g in 2 days. In order to investigate the strains' colonizing and distributing in soil, we marked PJ07 with green fluorescence protein gene(gfc) by transform and later illuminant enzyme gene(luxAB) by tri-parents mating. But its heredity was not stable.According with above outcome the effect of mixed inocuila were researched. Statistical analysis showed that the effect of mixed inocula beared a significant diference compared with control in maize, cole and tomato, whose grais dry weight were respectively 1 time, 64% and 82% more than control. And thejre is a significantly deference in term of this competence among microbial fertilizer from Shanghai and Hebei except for that it was correspond with one from Beijing.
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