Occurrence of polycyclic aromatic compounds and potentially toxic elements contamination and corresponding interdomain microbial community assembly in soil of an abandoned gas station

Abstract

Bacteria, archaea and fungi usually coexist in various soil habitats and play important roles in biogeochemical cycle and remediation of contamination. Despite their significance, their combined bioassembly pattern, ecological interactions and driving factors in contaminated soils still remain obscure. To fill the gap, a systemic investigation on the characteristics of microbial community including bacteria, archaea and fungi, assembly patterns and environmental driving factors was conducted in an abandoned gas station soils which were contaminated by polycyclic aromatic compounds and potentially toxic elements for decades. The results showed that the soils were contaminated excessively by benzo[a]pyrene (0.46-2.00 mg/kg) and Dibenz[a,h]anthracene (0.37-1.30 mg/kg). Multitudinous contaminant-degrading/resistant microorganisms and unigenes were detected, indicating potential of the soils to mitigate the pollution. Compared with fungi and archaea, the bacteria had higher community diversity and were more responsive to seasonal shifts. Functional genes (nidB, nahAb, nahAa, adhP, adh, adhC, etc.) involved in biodegradation were highly enriched in summer (1.96% vs 1.80%). The co-occurrence network analysis showed summer communities exhibit a more robust network structure and positive interactions than winter communities. The fungi Neocucurbitaria, Penicillium, Fusarium, Chrysosporium, Knufia, Filobasidium, Wallemia and Rhodotorula were identified as the keystone taxa, indicating that fungi also had important positions in the interdomain molecular ecological networks of both seasons. The network topological properties and |βNTI| (66.7%-93.3% greater than 2) results indicated the deterministic assembly processes of the microbial communities in the contaminated soil. Acenaphthylene, benzo[b]fluoranthene, indeno[1,2,3-cd]perylene, benzo[g,h,i]pyrene and 9-fluorenone were the key environmental factors driving the deterministic assembly processes of the interdomain microbial community in the contaminated soil. These findings extended our knowledge of interdomain microbial community assembly mechanisms and ecological patterns in natural attenuation and provide valuable guidance in associated bioremediation strategies.

Keywords: Co-occurrence network; Gas station; Natural attenuation; Polycyclic aromatic hydrocarbons; Soil microbial community.