Desert soils bioremediation with autochthonous thermotolerant/thermophilic bacteria

To investigate the potential of autochthonous bioaugmentation in enhancing the bioremediation of oil-contaminated soils at high temperatures, pristine Kuwaiti desert soil samples were contaminated with oil and bioaugmented with four autochthonous thermotolerant/thermophilic hydrocarbonoclastic bacteria, individually and as consortia. Culturable bacterial cells increased in the second half of the bioremediation process, which lasted for a year, in mesophilic and thermophilic communities. 49 hydrocarbonoclastic bacterial strains were recovered from all treated soil samples. Ten were thermophilic, growing only at 50?, while six were thermotolerant, growing at 30 and 50?, and the remaining were mesophiles. Culturable communities were somewhat similar during the same season of bioremediation in all treated soil samples, even those without bioaugmentation. The mesophilic community mainly consisted of the genera Streptomyces, Arthrobacter, Microbacterium, Nocardioides, Dietzia, and others, while Aeribacillus, Amycolatopsis, Nocardioides, and others made up the thermophilic community. Throughout the whole year of the bioremediation process, none of the bacterial strains used as inoculants could be cultivated from the bioaugmented soils. Molecular analysis revealed that the three largest bacterial phyla, Actinobacteria, Firmicutes, and Proteobacteria, formed 89% of the samples' bacterial communities. Incubation time rather than treatments primarily shaped the composition of these communities. There was a statistically insignificant difference in the rate of oil degradation between bioaugmented and unbioaugmented soils. This study shed light on the diversity of hydrocarbonoclastic microbial populations in the Kuwaiti desert, which improves their oil-biodegradation potential at high temperatures. However, the dynamic nature of these populations makes it difficult for any introduced members to be accepted.