Biochar-based sustained coenzyme delivery for enhanced petroleum hydrocarbon biodegradation

Petroleum contamination poses a persistent threat to ecosystems and human health because of its environmental persistence and ecological toxicity. To improve the efficiency of petroleum bioremediation through bioaugmentation, a biochar-based coenzyme activator (BC-VB) was developed by loading thiamine, riboflavin, and niacin onto biochar to provide a sustained supply of coenzyme precursors for the petroleum-degrading consortium B10. Under the optimized conditions, the BC-VB system achieved a crude oil degradation efficiency of 66.73 % at an initial concentration of 1000 mg·L^-1, representing a 17.97 % improvement over the B10 treatment. Characterization analyses confirmed the successful immobilization of the vitamins within the pores and on the surface of biochar, enabling their sustained release. Mechanistic investigations demonstrated that BC-VB enhanced the activities of key hydrocarbon-degrading and antioxidant enzymes while promoting extracellular electron transfer and energy metabolism. GC-MS analysis showed that BC-VB more effectively promoted the degradation of medium- and long-chain alkanes. Metatranscriptomic analysis further revealed the upregulation of genes involved in hydrocarbon degradation, coenzyme metabolism, substance transport, and antioxidant defense, thereby facilitating the oxidation and mineralization of petroleum hydrocarbons. In soil remediation experiments, BC-VB significantly enhanced the bioaugmentation performance of consortium B10, achieving a petroleum removal efficiency of 78.62 % within 60 days while improving the microbial community structure and metabolic functions. Overall, BC-VB synergistically enhanced petroleum hydrocarbon bioaugmentation through sustained coenzyme supply and multi-pathway metabolic regulation, providing an efficient strategy for the bioremediation of petroleum-contaminated environments.