| K,P and Si can be released from soil minerals by silicate bacteria,then they could be absorbed by plants directly. The main role of silicate bacteria is to help plant uptake nutrient element and produce various physiological active material.After implanted by nitrogen ions with energy 10keV and dose from 5.2×1014 N+/ cm2 to 18.2×1014 N+/ cm2,sixteen silicate bacteria mutants were screened out firstly in medium with nitrogen,then strain S05,which the ability of releasing K from silicate minerals rose by 68.48% compared with the original strain(LTF-22),was obtained by roseite culture with different pH value(pH4.0~9.0)and different salinity(0.5%~4.0%NaCl). The genetic test showed that S05 was stable. The colony growing on the medium without nitrogen is round,convex,smooth and wet. The viscosity of the colony declined compared with LTF-22. Strain S05 could grow well on the feldspar and non-nitrogen mediμm,so it was capable of releasing potassium and azotification as well. Strain S05 appears as rods and yields ellipsoidal spores observed with optical microscope. The ultrastructure research showed that the cells of strain S05 are thin,irregular and loose. It grew well with glucose,maltose and saccharose as its sole carbon source and with NH4+ and NO3- as nitrogen source respectively. Its physiological and biochemical characters,salt tolerance,antibiotic resistance,temperature sensitivity and K releasing capability were determined. It was found that strain S05 was more capable of releasing potassium and growing well in acid or basic soil at high temperature. The flask shake experiment showed that the content of soluble potassium was increased by 68.48% and 857.98% respectively,compared with CK1 and CK2. Strain S05 could survive in the medium with 2.5% NaCl and grow well at high temperature ranging from 35℃- 55℃. The effect of strains S05 on growth and GS activity of rice were also studied by pot culture experiments. It has been found that root height,dry weight and GS activity of rice treated with S05 rose 40.03%,32.27%and 101.13% respectively,compared with CK2;The content of available K of test team increased 36.97%,compared with CK1(treated with LTF-22). After native -PAGE,the determination of GS isoforms in the gel were carried out with activity staining. Seven bands of GS isoforms in rice root,which treated with strain S05,were clearly detected,and GS activity of GS5 and GS4 bands were higher than other bands. The content of available K in rice rhizosphere,cultured in pot and treated with S05,rose 36.97%and 219.06%respectively,compared with CK1 and CK2. |
