Fifteen bacterial isolates were isolated from a watering canal at Al Hadady-Damrou, Kafr El-Sheikh Governorate, Egypt (31.3°N 30.93°E). The screening process was achieved based on nitrogenase activity. The most potent bacterial isolate (B9) was tested as plant-growth-promoting rhizobacteria (PGPR). Ultrastructural, cultural, biochemical characteristics and 16S rDNA partial sequence were used for the isolate identification and characterization. From the 16S rRNA gene sequencing results, the nearest bacterial species to our isolate was Achromobacter marplatensis B2 (T), EU150134.1, with 97% matching. The sequence was submitted to the NCBI website with the accession number GenBank: KM491552.1. In vitro analysis revealed that the isolate under study is non-pathogenic (virulence factors-free) and capable of producing indole acetic acid (IAA), gibberellin (GA3) and solubilizing rock phosphate. Under greenhouse conditions, tomato inoculation with the obtained Achromobacter sp. EMCC1936 significantly increased vegetative growth, yield parameters and endogenous phytohormones content as compared with common free diazotrophic PGPR, Azotobacter chroococcum EMCCN1458. It was deposited in Microbiological Resource Center for public use with number (EMCC1936). Data revealed the importance of soil inoculation with the obtained isolate and of its role in increasing soil enzymatic activity. These features fulfill the isolate to be used as a PGPR for various crops. |
