Bacterial Communities Associated with Crude Oil Bioremediation through Composting Approaches with Indigenous Bacterial Isolate

SIMPLE SUMMARY: Crude oil contamination of soil has affected human health and the environment. Several approaches have been explored as a choice to alleviate such contamination. The microbial community is known to play a role in several activities in the soil, including the degradation of pollutants. Composting approaches are used in this sense to provide nutrients for soil microorganisms and to introduce an exogenous community of microorganisms, to further facilitate the process. In this work, we aim to investigate the role of the microbial community in degrading crude oil-contaminated soil using fruit-based composting. To make it more interesting, a newly isolated indigenous crude oil-degrading bacterium was also added to one of the composted treatments. The composted treatments showed high efficiencies of crude oil bioremediation at 78.1–83.84%, which was around 6–6.5 times higher than that of the contaminated soil without composting materials. The bacterial community analysis indicated that there was a significant difference in bacterial composition between the non-compost and composted treatments, confirming that different communities of microorganisms resulted in different degradation efficiencies. Altogether, the fruit-based composting approach is an effective method for crude oil bioremediation in soil. ABSTRACT: In this study, we aim to investigate the efficiency of crude oil bioremediation through composting and culture-assisted composting. First, forty-eight bacteria were isolated from a crude oil-contaminated soil, and the isolate with the highest crude oil degradation activity, identified as Pseudomonas aeruginosa, was selected. The bioremediation was then investigated and compared between crude oil-contaminated soil (S), the contaminated soil composted with fruit-based waste (SW), and the contaminated soil composted with the same waste with the addition of the selected bacterium (SWB). Both compost-based methods showed high efficiencies of crude oil bioremediation (78.1% and 83.84% for SW and SWB, respectively). However, only a slight difference between the treatments without and with the addition of P. aeruginosa was observed. To make a clear understanding of this point, bacterial communities throughout the 4-week bioremediation period were analyzed. It was found that the community dynamics between both composted treatments were similar, which corresponds with their similar bioremediation efficiencies. Interestingly, Pseudomonas disappeared from the system after one week, which suggests that this genus was not the key degrader or only involved in the early stage of the process. Altogether, our results elaborate that fruit-based composting is an effective approach for crude oil bioremediation.