Author(s)

K. Majki, S. Moustafa, A. S. Al-Dousari, E. Al-Saleh

Abstract

Crude oil spills into the environment such as that of Kuwait cause health and ecological problems which necessitates the cleanup of such pollution by efficient methods such as bioremediation. However, the associated heavy metals such as arsenic with crude oil pollution exert inhibitory effects on bioremediating agents for instance soil microbiota leading to hindered bioremediation. In the current study, the tolerance of two dominant crude oil-degrading bacteria in Kuwaiti soil, Acinetobacter spp. a Gram-negative bacteria and Nocardia spp. a Grampositive bacteria, to varying concentrations of arsenate and arsenite was investigated. Results showed the higher potentials of Nocardia spp. to resist the inhibitory effects of added arsenic compounds. Also, arsenite demonstrated significantly higher inhibitory effects on bacterial growth and activity compared to those of arsenate. Additionally, determination of the crude oil mineralization potentials of isolated bacteria demonstrated the significantly higher potentials of Nocardia spp. to mineralize crude oil in presence of arsenic compounds. Moreover, the phylogenetic assessment of isolated strains of Acinetobacter and Nocardia using 16S-RFLP analyses showed the higher diversity of Nocardia strains compared to Acinetobacter. Thus, this study demonstrated the variant effects of arsenic species on the growth and activity of different crude oil-degrading bacteria. Also, results indicated that, the potential of crude oildegrading bacteria to tolerate the inhibitory effects of heavy metals, such as arsenic, could accelerate the bioremediation of crude oil pollution.

Keywords

Crude oil-degrading bacteria, Gram-negative bacteria, Grampositive bacteria, Acinetobacter spp, Nocardia spp, arsenite, arsenate