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During a study of endophytic nitrogen-fixing bacteria present in the wild rice species Oryza alta, eight novel isolates were obtained from surface-sterilized roots and classified in the genus Rhizobium on the basis of almost-complete 16S rRNA gene sequence analysis. These strains can nodulate Phaseolus vulgaris and Glycine max. The highly similar protein patterns, DNA fingerprint patterns of insertion sequence-based PCR (IS-PCR) and DNA-DNA hybridizations showed that these novel isolates were members of the same species. The closest phylogenetic relatives of the representative strain Alt 505T of the novel group were Rhizobium etli CFN 42 T and Rhizobium indigoferae CCBAU 71714 T , with 96.2 and 96.0 % 16S rRNA gene sequence similarity, respectively. Low DNA-DNA relatedness with the type strains of R. etli, R. indigoferae, Rhizobium hainanense, Rhizobium mongolense and Rhizobium galegae and differences in IS-PCR fingerprinting patterns, SDS-PAGE of proteins, antibiotic resistance, phenotypic tests and comparison of cellular fatty acids with Rhizobium species indicated that the novel group of isolates were distinct from previously described species. Based on these results, we propose to place them in a novel species, as Rhizobium oryzae sp. nov. The type strain is Alt 505 T (5LMG 24253 T 5CGMCC 1.7048 T ).

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Antioxidizing enzymes (superoxide dismutase, catalase, and glutathione peroxidae) are important enzymatic systems used to degrade hydrogen peroxide into water and oxygen, thereby lowering intracellular hydrogen peroxide levels. Entomopathogenic fungi display increased activities of antioxidizing enzymes during growth and germination, which is necessary to counteract the hyperoxidant state produced by oxidative metabolism. We studied the influence of different carbon sources on antioxidizing enzyme production by Isaria fumosorosea to determine the importance of antioxiding enzymes induction in fungal germination, stress tolerance and virulence. Conidia produced by colonies grown on hydrocarbons showed higher rates of enzyme activities compared to the control and the enzyme activities of the conidia produced on n-octacosane were higher than all the other treatments. The lipid peroxidation activities were observed as an indicative marker of oxidative damage to cells and the lowest levels of lipid peroxidation activities were observed for n-octacosane treatment. The increased enzyme activities of n-octacosane- grown conidia were accompanied by higher levels of resistance to exogenous hydrogen peroxide, reduction in germination time and higher virulence against Spodoptera exigua. Our study has helped to identify that increased activities of antioxidizing enzymes can improve the germination and tolerance to antioxidant stress response of I. fumosorosea.