Isolation and characterization of endophytic bacteria from wild and traditionally cultivated rice varieties

Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogen etic analyses based on 16S rDNA revealed a wide divergence among the isolat es, However, the most frequently isolated groups were Methylobacterium sp. in the alpha-subdivision of Proteobacteria, and Curtobacterium sp. in the h igh G+C Gram-positive group. Various phenotypic traits that are expected to be involved in the persistence and functions of the bacteria were analyzed : Most of the isolates from rice excreted pectinase, were motile, and showe d an osmotic resistance to 0.6 M sucrose, These traits may be involved in e ndophytic characteristics in rice, About 50% of the isolates showed a cellu lase activity, A few isolates fixed nitrogen, produced indole-3-acetic acid , and formed capsules. These activities were partially correlated with the phylogenetic group.