Paenibacillus terrae new strain NK3-4 and its functions

Abstract:

[Objective] The aim of this paper was to obtain a bacterial strain which has the ability of degrading mineral phosphorus, potassium and silicon, controlling plant disease, and fixing nitrogen. [Methods] Soil was collected from rhizosphere of soybean (Glycine max), then selected medium supplemented with potash feldspar was used to enrich bacterial strains exhibiting ability of degrading silicate. Dual-culture plate method was used to gain a bacterium which had the strongest ability of antifungal activity to the soybean root rot pathogen Fusarium oxysporum. After that, the activity of degrading mineral potassium, silicon, and phosphorus of the bacterium was tested by shake flask method, meanwhile the optimized Ashby’s medium was used to test the activity of fixing nitrogen. The isolated strain was identified through morphology observation, physiological and biochemical tests and 16S rRNA gene sequence analysis. [Results] A bacteria strain named NK3-4 was isolated from rhizosphere soil of healthy soybean in field. The bacterium inhibited F. oxysporum growth with inhibiting belt of 8.0 mm width on plate. The concentration of dissoluble potassium in medium contained potash feldspar was 15.0 mg/L higher than that in medium without potash feldspar, and the concentration of dissoluble silicon was 131.7% higher than the un-inoculated control after cultivation for 24 hours. The concentration of dissoluble phosphorus was 4.8 times of the un-inoculated control in medium with calcium phosphate as only phosphoric source after cultivation for 8 days. The concentration of dissoluble nitrogen was 4.6 times of the uninoculated control in Ashby’s medium after cultivation for 15 days, and the nitrogen content fixed in the bacterial organism was 12.7 mg in one liter of medium. The identification showed that the NK3-4 strain was a new strain belongs to Paenibacillus terrae. [Conclusion] Strain NK3-4 is a new strain of P. terrae with multifunctions, it can be used as a potential microorganism for exploit of biofungicide and biofertilizer.