The phylogeny of fluorescent pseudomonads in an unflooded rice paddy soil

The purpose of this research was to determine the diversity and distribution of fluorescent pseudomonads in an unflooded rice paddy soil. A region of the 16S ribosomal RNA gene from isolates was amplified using PCR and subsequently analysed by sequence analysis for bacterial identification and phylogenetic classification. A total of 117 fluorescent pseudomonads, representing between 10 and 21 species, were isolated from two sampling sites within the same paddy (designated as soils C and S). The isolates were found to be ≥96% homologous with known sequences, and were most closely related to the followingPseudomonas species:P. antarctica, P. costantini, P. extremorientalis, P. frederiksbergensis, P. kilonensis, P. koreensis, P. lini, P. mandelii, P. poae, P. rhodesiae, andP. veronii. Of these matches, the bulk of the isolates (49%) were affiliated withP. mandelii. In soils C and S, phylogenetic analysis revealed that 35 and 82 isolates co-clustered with 39 and 59% of 66 fluorescent pseudomonad type strains, respectively.