Sustainable long-alkanes biodegradation with moderate pre-oxidation in soil

This study aimed to investigate the mechanism of sustainable biodegradation of long-alkanes with moderate pre-oxidation in soil. Moderate pre-oxidation was performed with two consecutive doses of 1.35 mL 30% of H₂O₂ (225 mM) in two soil. After moderate pre-oxidation, the experiment of sustainable biodegradation of long-alkanes during 80 d was conducted. Then, long-alkanes relative activity coefficient (K), NH₄⁺-N allocation (G) and the performance of hydrocarbon degraders (E) was calculated. Long-alkanes were sustainably biodegraded with moderate pre-oxidation (1765 mg/kg, 2438 mg/kg and 2672 mg/kg). Long-alkanes biodegradation (8723 mg/kg) with moderate pre-oxidation was 2.5 folds of excessive pre-oxidation. The average increment in long-alkanes biodegradation with moderate pre-oxidation was 30–38% as K values improved (0.28–0.48). The bacterial destruction D decreased to 14–17% and hydrocarbon degraders activity increased to 0.065 mol CO₂/kg with moderate pre-oxidation. <i>Basidiomycota</i> and <i>Acinetobacter sp</i>. showed high tolerance with moderate pre-oxidation and remained dominant strains throughout the bioremediation. NH₄⁺-N consumption played an essential role as nutrients in growth of hydrocarbon degraders (<i>Basidiomycota</i> and <i>Acinetobacter sp</i>.). Then, high and sustained E was achieved with decreased D and elevated hydrocarbon degraders activity, resulting in high K. So, long-alkanes sustainably increasing biodegraded under high E assisted with elevated G with moderate pre-oxidation.

本研究旨在探究土壤中经适度预氧化处理的长链烷烃的可持续生物降解机制。实验采用两次连续施加剂量为1.35 mL、浓度30%的过氧化氢（H₂O₂，225 mM）的方式，对两份土壤开展适度预氧化处理。完成适度预氧化后，开展了为期80天的长链烷烃可持续生物降解实验。随后计算得到长链烷烃相对活性系数（K）、铵态氮（NH₄⁺-N）分配量（G）以及烃类降解菌的降解效能（E）。经适度预氧化处理的长链烷烃实现了可持续生物降解，降解量分别为1765 mg/kg、2438 mg/kg及2672 mg/kg。经适度预氧化处理的长链烷烃生物降解总量达8723 mg/kg，为过度预氧化组的2.5倍。随着K值从0.28提升至0.48，适度预氧化组的长链烷烃生物降解量平均提升了30%~38%。经适度预氧化处理后，细菌损伤率（D）降至14%~17%，同时烃类降解菌的活性提升至0.065 mol CO₂/kg。担子菌门（Basidiomycota）和不动杆菌属（Acinetobacter sp.）对适度预氧化处理具有较高耐受性，且在整个生物修复过程中始终为优势菌株。铵态氮（NH₄⁺-N）的消耗作为营养物质对烃类降解菌（担子菌门和不动杆菌属）的生长起到关键作用。随着细菌损伤率降低、烃类降解菌活性提升，可获得高且持久的E值，进而促成高K值。因此，在适度预氧化处理、提升的G值以及高E值的协同作用下，长链烷烃实现了可持续的逐步降解。