radicincitans D5/23T (about 9 log CFU per plant), but not at a lower level, i.e. 8 log CFU per plant [19]. Rice plants growing in non-sterile soil revealed reduced fresh weights, i.e. 0.31 g (±0.07) for uninoculated plants and 0.30 g (±0.08) for inoculated

ones. The initial microbiota in the unsterilized soil thus appeared to impair the growth of rice plants, when compared to sterilized soil. In a recent review, Reinhold-Hurek and Hurek [28] addressed the recalcitrance of bacterial endophytes to cultivation. Many abundant endophytes that are active in planta are still uncultivable. In addition, the already cultivated ones are often scarcely culturable in planta. We here provide evidence for the existence of two novel culturable find more Enterobacter species in the rice endosphere. The group-I strain REICA_142TR was remarkable, as it is easily cultivated DihydrotestosteroneDHT in vitro as well as in planta. Besides, this strain was related to a dominant gene sequence found in the library representing rice root endophytes [14]. Conclusions Arguments for the definition of two novel Enterobacter species On the basis of the foregoing data and arguments for the importance and relevance of rice-associated Enterobacter species,

we propose that the group-I and group-II strains are classed into two novel species that should – considering the genus is intact at this point in time ��-Nicotinamide in vivo – be placed inside the genus Enterobacter. First, both groups are internally very homogeneous, and, by all criteria used, they class as solid taxonomic units. Secondly, Smoothened on the basis of (1) the 16S rRNA gene sequence similarity, (2) the rpoB gene sequence similarity

and (3) the DNA:DNA hybridization data, we clearly discern the appearance of two novel groups (radiations) within the genus Enterobacter. These two strain groups are thus proposed to form two novel species, denoted Enterobacter oryziphilus and Enterobacter oryzendophyticus. Both groups are likely to have their preferred niche in association with rice plants. They may play key roles in the rice endosphere, providing an ecologically-based justification for their definition. The descriptions of the two species are given below. Description of Enterobacter oryziphilus sp. nov Enterobacter oryziphilus: o.ry.zi´phi.lus. L. nom. n. oryza, rice; philus (from Gr. masc. adj. philos), friend, loving; N.L. masc. adj. oryziphilus, rice-loving. Cells are Gram-negative, motile, straight rods (0.9-1.0 μm wide by 1.8-2.9 μm long) and occur singly or in pairs. Mesophilic, chemoorganotrophic and aerobic to facultatively anaerobic. Colonies on TSA medium are beige pigmented, 2–3 mm in diameter and convex after 24 h at 37°C. Growth occurs at 15-42°C (optimum 28-37°C). NaCl inhibits growth at concentrations above 5%. Growth was detected on C and O media. Cytochrome oxidase negative and catalase positive.