Isolation, Selection And Detection Of Associative Nitrogen Fixation Bacteria In Rhizosphere Of Sisal

Sisal is an important tropical economic crop. However there are many problems in the production such as serious lack of nitrogen fertilizer, high chemical fertilizer cost and its low utilization ratio. We researched the associative nitrogen fixation bacteria in sisal rhizosphere, which were sampled from Changjiang county in Hainan province, Fusui county in Guangxi province and Leizhou city in Guangdong province, in order to provide basis for producing special microbial N fertilization for sisal and solving the fertilizer lack, high cost in sisal's planting in future. The LB, NFM, CCM, Ashby and modified Dobereiner mediums were used to isolate, select and detect the bacteria by Gas Chromatography. Morphologic status, aerobism, different carbon source usage and partial biochemistry reaction detection were done. PKO, Meng Jinna organic medium and modified CCM were used to research the phosphorus solubility and the plant hormone character by Phosphate Solubilization Loop method and Colorimetry respectively. On the basis of that,16S rDNA sequence of the sisal rhizosphere nitrogen fixation bacteria was analyzed. The results showed that:1,There were 50 nitrogen fixation bacteria strains isolated. The nitrogenase activity ranges from 1.8002 nmol/mL·h to 1765.6590 nmol/mL·h. There were 12 strains, the nitrogenase activity of which above 1000nmol/mL·h. The nitrogenase activity of strain ASN004 was the highest,1765.6590nmol/mL·h.2,Among the 12 strains, the nitrogenase activity of which was above 1000nmol/mL·h, strain ASN006 and ASN023 showed better ability in terms of dissolving organic and inorganic phosphorus. Strains ASN004 showed better ability in terms of dissolving organic phosphorus, good ability in that of inorganic phosphorus. Strain ASN012 showed good ability in dissolving both inorganic and organic phosphorus. Strain ASN030 showed good ability in dissolving organic phosphorus. Meanwhile strain ASN002,ASN003,ASN004,ASN006,ASN012,ASN023 and ASN037 showed higher ability in producing growth hormones.3,The blast comparing analysis on NCBI net after 16SrDNA sequence analysis of the sisal rhizosphere nitrogen fixation bacteria showed that:strain ASN001,ASN003,ASN004,ASN006,ASN035,ASN036 belonged to Klebsiella; Strain ASN002,ASN005,ASN012,ASN017,ASN023,ASN029 were Enterobacter cloacae complex;Strain ASN0101,ASN040,ASN044 were Terrimonas; Strain ASN013,ASN018,ASN031 belonged to Sinorhizobium;Strain ASN022,ASN026,ASN027 were Burkholderia;Strain ASN028,ASN041,ASN045 belonged to Bacillus.4,Strains ASN006 (Klebsiella) and ASN023 (Enterobacter cloacae complex) showed outstanding abilities in nitrogen fixation, dissolving phosphous and producing growth hormones. they can ready for N-biofertilizer producing for sisal. There were better stains for producing sisal microbial fertilizer.