Bacterial community bioremediation of oil-contaminated soils in the hyper-arid Arava Valley

Oil pollution has become a severe problem in soil ecology. The soil bacterial consortia play a critical role in governing the biodegradation of total petroleum hydrocarbons (TPHs), in particular polycyclic aromatic hydrocarbons (PAHs). Nowadays, bioremediation is widely considered the most desirable procedure for restoration of oil-contaminated soil. The main objective of the present study was to examine the change in bacterial diversity in dryland soils contaminated by oil, using a high-throughput sequencing technique. The Illumina MiSeq high-throughput sequencing technique was used to study the bacterial abundance, diversity, and structural change in oil-contaminated soil in a hyper-arid region. The results showed that soil bacterial abundance and diversity significantly declined following oil pollution. The dominant phyla (i.e., Proteobacteria and Patescibacteria ) in the petroleum-contaminated soils, are oil-associated and hydrocarbon-degrading bacteria. The abundance of Proteobacteria phyla is 33% higher in contaminated soil compared to the non-polluted, control samples. For Patescibacteria phyla it around 2.5% higher in contaminated soil compared to the control samples. The opposite trend was noted for Actinobacteria ( 8%), Chloroflexi (12%), Gemmatimonadetes (3%) and Planctomycetes (2%) phyla; their abundance was lower in contaminated soil compared to the control samples. The study results provide new insights and may facilitate in designing appropriate biodegradation strategies to mitigate the serious problems of oil contamination of desert soils.