Assessing Antibiotic Resistance Genes in Pristine, Oil-contaminated, and Bioremediated Soils

Crude oil exploration to meet the growing global energy demand is persistently harming the environment. Bioremediation of crude oil-contaminated soil using organic substrate (biostimulation) has been considered sustainable and cost-effective. However, the choice of biostimulation materials raises concerns about potentially increasing ARGs in treated soils. Microcosms consisting of soil samples with and without crude oil and amended with manure or compost were set up to investigate the effect of these amendments on ARGs and hydrocarbon degradation. These microcosms were kept at 15°C, and subsamples were taken for DNA extraction and molecular analyses within the first 12 weeks. ARGs are being assessed and compared in soil exposed to oil and manure or compost treatments using PCR with primers targeting specific ARGs of public health importance. Among the ARGs assessed, sul1 was detected in the pristine, compost and manure treated soil at the start of the experiment and after 12 weeks. In contrast, sul2 was absent in pristine soil but present in compost- and manure-treated soil at the start and after 12 weeks. While ARGs, tetW and ermF were exclusively present in the manure-treated soil at the start and 12 weeks of incubation. However, tetO was detected in pristine and manure-treated soil at the start but was absent in all soil samples at week 12. Further molecular analysis such as metagenomics is required to quantitatively monitor the impact of oil, compost, and manure on ARG pattern and microbial community. Geochemical analysis is being conducted to evaluate hydrocarbon degradation within the samples.