Enhanced plant-assisted microbial remediation of oil drill cutting from arid areas

Drill cuttings contain a mixture of hydrocarbons and metal(loid)s. Bioremediation represents a promising strategy to reduce their environmental impact. Nonetheless, the warm and saline conditions that prevail in areas where drill cuttings are produced limit the microbial degradation capacities. Strategies to manage microbial community are thus required in order to broader their degradation efficiency. We hypothesized that plants (Lygeum spartum, Helianthus annuus) drive microbial organization during drill cuttings treatment, resulting in different hydrocarbon-removal capacities. Drill cuttings, mixed with manure and sand, were maintained 120 days in greenhouse mesocosms. The plants improved hydrocarbon removal, reaching more than 85%, reducing also the bioavailable metal(loid)s fraction. Plant specific microbial assemblages, revealed by 16S rRNA metabarcoding, owned "specialist" taxa potentially involved in the degradation of distinct hydrocarbon fractions: Moheibacter, Devosia, Bacillus, Lysinibacillus, and Pricia specific to Helianthus annuus, while Luteibacter specific to Lygeum spartum. Plant-assisted remediation strategy is encouraged to manage microbial community for oil drill cuttings treatment.