Data_Sheet_1_Field scale biodegradation of total petroleum hydrocarbons and soil restoration by Ecopiles: microbiological analysis of the process.pdf

Ecopiling is a method for biodegradation of hydrocarbons in soils. It derives from Biopiles, but phytoremediation is added to biostimulation with nitrogen fertilization and bioaugmentation with local bacteria. We have constructed seven Ecopiles with soil heavily polluted with hydrocarbons in Carlow (Ireland). The aim of the study was to analyze changes in the microbial community during ecopiling. In the course of 18 months of remediation, total petroleum hydrocarbons values decreased in 99 and 88% on average for aliphatics and aromatics, respectively, indicating a successful biodegradation. Community analysis showed that bacterial alfa diversity (Shannon Index), increased with the degradation of hydrocarbons, starting at an average value of 7.59 and ending at an average value of 9.38. Beta-diversity analysis, was performed using Bray-Curtis distances and PCoA ordination, where the two first principal components (PCs) explain the 17 and 14% of the observed variance, respectively. The results show that samples tend to cluster by sampling time instead of by Ecopile. This pattern is supported by the hierarchical clustering analysis, where most samples from the same timepoint clustered together. We used DSeq2 to determine the differential abundance of bacterial populations in Ecopiles at the beginning and the end of the treatment. While TPHs degraders are more abundant at the start of the experiment, these populations are substituted by bacterial populations typical of clean soils by the end of the biodegradation process. Similar results are found for the fungal community, indicating that the microbial community follows a succession along the process. This succession starts with a TPH degraders or tolerant enriched community, and finish with a microbial community typical of clean soils.

生态堆修复（Ecopiling）是一种用于土壤烃类污染物生物降解的技术。该方法源自生物堆（Biopiles）技术，同时在氮肥生物刺激与本地菌株生物强化的基础上加入了植物修复（phytoremediation）环节。我们在爱尔兰卡洛郡利用受烃类严重污染的土壤构建了7组生态堆修复体系。本研究的核心目标为解析生态堆修复过程中微生物群落的动态变化。在长达18个月的修复周期内，脂肪烃与芳香烃的总石油烃（total petroleum hydrocarbons, TPH）平均降解率分别达到99%和88%，证实了该技术的生物降解效果优异。群落分析结果显示，细菌α多样性（以Shannon指数（Shannon Index）衡量）随烃类降解进程逐步提升，初始平均数值为7.59，最终平均数值达9.38。β多样性分析采用Bray-Curtis距离（Bray-Curtis distances）与主坐标分析（PCoA ordination），前两个主成分分别解释了观测总方差的17%与14%。结果表明，样本聚类主要依据采样时间，而非生态堆组别。该规律得到层级聚类分析（hierarchical clustering analysis）的验证：同一采样时间点的绝大多数样本可聚为独立分支。本研究采用DSeq2工具分析修复初期与末期生态堆内细菌种群的差异丰度。实验初始阶段，石油烃降解菌群占据优势；但在生物降解过程结束时，此类菌群已被清洁土壤典型细菌种群所替代。真菌群落亦呈现相似的演替规律，表明微生物群落在整个修复过程中发生了连续性演替：初始阶段为富集石油烃降解菌或耐受菌的群落，最终演变为清洁土壤典型微生物群落。