Experiment and Practice Innovation Education Center, Beijing Normal University at Zhuhai, Zhuhai, 519087, China.
College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
Environ Sci Pollut Res Int. 2022 Nov;29(55):83060-83070. doi: 10.1007/s11356-022-21246-2. Epub 2022 Jun 27.
Petroleum hydrocarbons are hazardous to ecosystems and human health, commonly containing n-alkanes and polycyclic aromatic hydrocarbons. Previous researches have studied alkane degraders and degrading genes under aerobic or anaerobic conditions, but seldom discussed them in the intermittent saturation zone which is a connective area between the vadose zone and the groundwater aquifer with periodic alteration of oxygen and moisture. The present study investigated the difference in alkane degradation efficiency, bacterial community, and alkane degrading gene diversity in aerobic, anaerobic, and aerobic-anaerobic fluctuated treatments. All biotic treatments achieved over 90% of n-alkane removal after 120 days of incubation. The removal efficiencies of n-alkanes with a carbon chain length from 16 to 25 were much higher in anaerobic scenarios than those in aerobic scenarios, explained by different dominant microbes between aerobic and anaerobic conditions. The highest removal efficiency was found in fluctuation treatments, indicating an accelerated n-alkane biodegradation under aerobic-anaerobic alternation. In addition, the copy numbers of the 16S rRNA gene and two alkB genes (alkB-P and alkB-R) declined dramatically when switched from aerobic to anaerobic scenarios and oppositely from anaerobic to aerobic conditions. This suggested that water level fluctuation could notably change the presence of aerobic alkane degrading genes. Our results suggested that alkane degradation efficiency, soil microbial community, and alkane-degrading genes were all driven by water level fluctuation in the intermittent saturation zone, helping better understand the effects of seasonal water table fluctuation on the biodegradation of petroleum hydrocarbons in the subsurface environment.
石油烃类物质对生态系统和人类健康具有危害性，通常含有正构烷烃和多环芳烃。先前的研究已经研究了在需氧或厌氧条件下的烷烃降解菌和降解基因，但很少在间歇饱和带（包气带和地下水含水层之间的连接区域，具有氧气和水分周期性变化）中讨论它们。本研究调查了在需氧、厌氧和需氧-厌氧波动处理中烷烃降解效率、细菌群落和烷烃降解基因多样性的差异。所有生物处理在 120 天的孵育后，均实现了超过 90%的正构烷烃去除。在厌氧条件下，碳链长度为 16 至 25 的正构烷烃的去除效率明显高于需氧条件下，这可以通过需氧和厌氧条件下不同的优势微生物来解释。波动处理的去除效率最高，表明在需氧-厌氧交替条件下，正构烷烃的生物降解加速。此外，当从需氧切换到厌氧条件时，16S rRNA 基因和两个 alkB 基因（alkB-P 和 alkB-R）的拷贝数急剧下降，而从厌氧切换到需氧条件时则相反。这表明水位波动可以显著改变好氧烷烃降解基因的存在。我们的结果表明，在间歇饱和带中，烷烃降解效率、土壤微生物群落和烷烃降解基因均受水位波动的驱动，有助于更好地理解季节性地下水位波动对地下环境中石油烃生物降解的影响。
