[Microbial Community Structure Shift During Bioremediation of Petroleum Contaminated Soil Using High Throughput Sequencing].

The shift in microbial community structure during the bioremediation of oil-polluted soil was analyzed by high-throughput sequencing. The results demonstrated obvious changes in the soil microbial community structure and diversity during bioremediation. The species richness and evenness of the microbial community decreased substantially due to the bioaugmentation treatment. Proteobacteria became the predominant phylum, with a relative increase in abundance from 37.44% to 87.44%. Pseudomonas was the most dominant genus, which increased in abundance from 2.99% to 76.37%. In the biostimulation treated soil, the relative abundance of Proteobacteria decreased from 37.44% to 10.90%, while the phylum Firmicutes increased from 9.16% to 35.32%. At the genus level, the relative abundances of Exiguobacterium and Promicromonospora decreased from 8.49% and 18.96% to 2.19% and 14.97%, respectively. Nocardioides and Bacillus became the dominant genera and increased from 5.56% and 0.29% to 28.95% and 22.70%, respectively. The results indicated that bioaugmentation substantially influenced the soil microbial diversity and community structure. Additionally, the biostimulation treatment maintained the balance in the soil microbial community structure. The stabilization of bacteria community structure is beneficial to petroleum biodegradation in the soil.

[Impacts of Bioremediation on Microbial Communities and Different Forms of Nitrogen in Petroleum Contaminated Soil].

A laboratory study was conducted to investigate the impacts of bioremediation on microbial communities and various nitrogen shifts in petroleum contaminated soil by using GC-MS and Illumia MiSeq technique. Results showed the concentrations of alkane reduced from 25987.8 mg·kg-1 to 12788.6 mg·kg-1, and the concentrations of polycyclic aromatic hydrocarbons (PAHs) decreased from 5322.9 mg·kg-1 to 2917.2 mg·kg-1. Illumia MiSeq results showed that soil microbial communities shifted significantly after remediation, and the relative abundance of some phylum of hydrocarbon degraders (Firmicutes, Bacterodetes), and some genus of degraders (Dietzia, Acinetobacter) increased. Besides, the contents of total nitrogen and ammonia nitrogen increased firstly and then decreased during remediation. However, the contents of nitrate nitrogen decreased at the early stage, and then kept stable in the later stage of remediation. It can be concluded that bioremediation effectively promoted petroleum hydrocarbon degradation, and the different fractional hydrocarbon degradation was related to the relative abundance of hydrocarbon degraders and available nitrogen contents.

[Remediation of Petroleum-Contaminated Soil Using a Bioaugmented Compost Technique].

Bioaugmented compost was created by inoculating petroleum-degrading bacteria into mature compost. The petroleum hydrocarbon degradation efficiencies were investigated by applying this enhanced compost to petroleum-contaminated soil under low temperatures. The results showed that the degrading bacteria can be enriched in the mature compost. After 30 d of remediation, the removal efficiency of TPH, alkanes, and PAHs in the soil was 27.0%, 19.6%, and 10.0%, compared to natural attenuation (CK), which was 4.5%, 9.5%, and 2.3%, respectively. In response to remediation, the relative abundance of Proteobacteria and Actinobacteria phyla decreased from 53.4% and 25.9% to 48.9% and 14.1%, respectively, and Bacteroidetes phylum increased from 5.0% to 24.5%. At the genus level, the relative abundance of Acinetobacter and Pseudomonas increased from 0.02% and 3.4% to 15.2% and 4.6%, respectively. The results indicated that the bioaugmented compost may efficiently facilitate and speed up the bioremediation of petroleum-contaminated soil under low-temperature conditions. Soil microbial diversity and structure of microbial communities are sensitive to the remediation.