Isolation of an Effective Nitrogen-Fixing Strain N1115 from Rice Rhizosphere by Rice Germ Lectin

Nitrogen is an essential element for plant growth as well as is the most significant yield-limiting element in many agricultural production systems. Therefore, it is worthy to isolate nitrogen-fixation bacteria from plant rhizosphere. Our purpose is to screen effective nitrogen-fixation bacteria that show affinity to rice germ lectin from the rice root. Ashby medium absence of nitrogen source was used to isolate nitrogen-fixation bacteria from rice rhizosphere. Then, the strains were re-screened by rice germ lectin labeled with fluorescein isothiocyanate. In this study, rice germ lectin was used as a tool to screen effective and nitrogen-fixation bacteria. The physiological and biochemical characteristics of the strain N1115 were evaluated as well as the 16SrRNA gene sequence. The results showed that strain N1115 had an affinity to rice germ lectin and could fix nitrogen with the efficiency of 9.217 0.148mg N/gG. Based on the analysis of 16S rRNA partial gene sequence, this strain was classified to Bicillus megaterium. Herein, we proposed a possible method for selecting effective PGPR to apply in research and development of biofertilizer.