Studies on nitrogen-fixing microorganisms in rice rhizosphere = 벼뿌리 부근에 서식하는 질소고정미생물에 관한 연구

Abstract

Nitrogen-fixing bacteria were isolated from the rice rhizosphere of various paddy fields in our country. The screening of 238 isolates for nitrogen-fixing ability resulted in the isolation of Enterobacter agglomerans NFB264 and three Klebsiella pneumoniae NFB3, NFB278, NFB320. Plasmids of various molecular weight from 1.7 to more than 84 Mai. were detected by agarose gel electrophoresis in three out of four isolates. But, these plasmids had not any nitrogenfixing genes. Hybridization experiments using Klebsiella pneumoniae M5al nitrogen-fixing genes, nifQ-K and /7//DH, as probes revealed the presence of homologous sequences in the chromosomal DNA of all isolates. However the restriction patterns of nif genes of the isolates by various restriction endonucleases were different to those of Klebsiella pneumoniae M5al.