Diesel degrading bacterial endophytes with plant growth promoting potential isolated from a petroleum storage facility

Thirteen (13) endophytic bacterial strains were isolated from Echinochloa crus-galli (Cockspur grass) and Cynodon dactylon (Bermuda grass) growing in an oil-contaminated site at a petroleum storage and transportation facility. Of the 13 strains assessed for their potential to degrade monoaromatic compounds (phenol, toluene, and xylene) and diesel and for their plant growth promoting (PGP) ability (phosphate solubilization, siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production), isolate J10 (identified as Pseudomonas sp. by 16S rRNA gene sequencing) was found to the best diesel biodegrader with the best PGP traits. The Monod model used for Pseudomonas sp. J10 growth kinetics on diesel fuel as the sole carbon source showed that the maximum specific bacterial growth rate was 0.0644h(-1) and the half velocity constant (K-s) was estimated as 4570mg L-1. The overall growth yield coefficient and apparent growth yield were determined to be 0.271g h(-1) and 0.127g cells/g substrate, respectively. Pseudomonas sp. J10 removed 69% diesel in four days as determined by gas chromatographic (GC) analysis. These findings could assist in developing an endophyte assisted efficient diesel biodegradation system using Pseudomonas sp. J10 isolated from Echinochloa crus-galli.