Functional attributes and response of bacterial communities to nature-based fertilization during hydrocarbon remediation

Abstract

This study offers a Nature-based Solutions (NbS) for the recovery of long-term oil-polluted soils. An NPK-type substituted organic fertilizer (SOF) was formulated using available nature-based materials, and its effect on bacterial diversity, richness and community composition investigated during the remediation of a long-term crude oil-impacted soil. Results obtained were compared to a control and a chemical fertilizer (CF) treatment. The rate of total petroleum hydrocarbons (TPH) degradation was observed to be highest in the SOF treatment (0.022 d – 1) compared to the CF (0.016 d – 1) and control treatments (0.001 d – 1). Improvement of bacterial diversity in the SOF treatment significantly correlated with pH and soil organic matter (SOM). Proteobacteria was the dominant phylum across all the treatment systems. Acidocella was dominant in both the control and CF treatments, while Brevundimonas and Alcanivorax were the most abundant genera in the SOF treatment. The bacterial community structure and composition were significantly differentiated (PERMANOVA, p ≤ 0.01) in the different treatment processes. Constrained redundancy analysis revealed that pH, SOM, calcium, TPH and potassium influences the bacterial community composition. Analysis of bacterial community interaction suggests that there was higher efficiency in information processing and chemical transmission in the SOF treatment compared to the CF treatment. PICRUSt2-based functional prediction revealed that dissimilatory/assimilatory nitrate reduction and denitrification were among biomarkers in the nutrient amended treatments, while enzymes for nitrogen fixation were differentially abundant in the control treatment. Overall, the findings of this study suggest that the formulated NbS-fertilizer might stimulate more rapid biodegradation by improving soil nutrients and the proliferation of diverse microbial species in oil-polluted soils.