Isolation and characterization of plant growth-promoting rhizobacteria and their effects on phytoremediation of petroleum-contaminated saline-alkali soil

This study aimed to isolate promising halotolerant and alkalotolerant plant growth-promoting rhizobacteria and to study their effects on the growth of tall fescue and phytodegradation efficiency in a petroleum-contaminated saline–alkaline soil. A total of 115 PGPR strains were isolated from the rhizosphere of tall fescue grown in petroleum-contaminated saline–alkaline soils. Of these, 5 strains indicating 1-aminocyclopropane-l-carboxylic acid deaminase activity >1.0 M α-KB mg−1 h−1 were selected for further studies. The isolate D5A presented the highest plant-growth-promoting activity and was identified as Klebsiella sp. It grew well on the Luria–Bertani medium containing 9% NaCl and at a pH range of 4–10. A pot experiment was then conducted to study the effect of isolates on phytoremediation. The results showed that inoculation of D5A promoted tall fescue growth and enhanced remediation efficiency in petroleum-contaminated saline–alkaline soil.