During rice growing season, the symptomless rice seeds from different paddy fields in Guilan province, Iran, were collected. After isolation of epiphytic and endophytic bacteria, 39 isolates including 19 epiphytes and 20 endophytes were selected based on the predominant characteristics. Five Operational Taxonomic Units (OTUs) were obtained based on PCR-RFLP of 16S r-DNA in these isolates. According to biochemical tests and partial sequencing of 16S-rDNA, in both epiphyte and endophyte bacteria of rice seeds, the most populated OTUs (V and II) were identified as Pantoea ananatisand Pseudomonas oryzihabitans,respectively. Six representative isolates from these two OTUs were selected to be evaluated for their abilities for rice seed germination and growth enhancement. Among them,P. oryzihabitanswas not beneficially effective. However, JpB1 isolate of P. ananatiswas considered to be the most effective plant growth promoting isolate, since it showed stable beneficial effects on most surveyed characteristics in both rice seed germination and growth enhancement experiments. Although, OpB3 isolate ofP. ananatisproduced IAA in higher amount and solubilized phosphate more than the other isolates followed by JpB1 and P. ananatisL3pB3 , it was not beneficially effective on rice seed germination. .
