Pseudomonas sesami sp. nov., a plant growth-promoting Gammaproteobacteria isolated from the rhizosphere of Sesamum indicum L.

Abstract

A novel Gram-stain negative, aerobic, motile, rod-shaped bacterium was isolated from Sesame (Sesamum indicum L.) rhizosphere soil. Based on the 16S rRNA gene similarity value (99.4-98.6%) obtained with phylogenetically closely related strains and through analyses of their house keeping genes (atpD, infB and rpoB), the strain SI-P133T was delineated among the species of the genus Pseudomonas and was subjected to polyphasic taxonomic analysis. It was a chemoorganotroph which grew at wide range of temperature (4-45°C), pH (5.5-9.5) and NaCl concentrations (0-7% (w/v). DNA-DNA hybridization values with closely related type strains DSM 9751T, DSM 19095T, DSM 21509T, ICMP 9151T and DSM 6929T ranged from 23.1 to 44.2%. The most abundant fatty acids were C16:0, C10:0 3-OH, summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c), C17:0 cyclo and C12:0 3-OH. The major isoprenoid quinone system was ubiquinone 9 (Q-9) and the G+C content was 61.3mol%. The major polar lipids of the strain SI-P133T were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. With regard to prospective use in agriculture, plant growth-promoting properties of the strain were tested and plant growth-promotion was demonstrated under in vitro conditions. Based on the various polyphasic taxonomic traits analysed, the strain SI-P-133T was novel and placed within the genus Pseudomonas. Hence we propose a novel species named Pseudomonas sesami sp. nov., for which the type strain is SI-P133T (=NCIMB 14519T=KCTC 22518T).