Impact of sub-zero temperatures on the fungal community composition and diversity in short-term petroleum polluted temperate soils

Climate change is already altering the temperate ecosystems and as a result these ecosystems are now subjected to increased incidence of freezing and warming events. To understand the impact of sub-zero temperatures on the fungal communities in temperate soils, three soils namely clean natural soil (CNS), short term diesel oil polluted (SDS) and crude oil polluted (SCS) from a temperate region in Northern China were subjected to freezing and thawing temperatures ranging from –20 to 0C for 32 days. This study monitors and compares the changes in fungal community composition and diversity in clean and short-term petroleum polluted soils at specific temperature points (20, 0, –10 and –20C) during the laboratory-controlled freeze-thaw experiments. Structural analysis of the fungal community with 18S RNA gene analysis revealed that the sub-zero temperatures caused distinct shifts in the fungal phylum composition of the temperate soils during soil freezing phase and thawing phase respectively. The community in CNS was most responsive to the sub-zero temperature changes among the studied soil types. The thawing sub-zero temperatures were characterized by decreased community richness in the clean soil while the short-term polluted soils SDS and SCS increased in richness. Overall, our results established that the fungal community composition and diversity in the polluted soil types were more adaptable to the sub-zero temperature variations during soil freezing and thawing conditions when compared to those in the clean natural soil, suggesting that the native fungal communities present in the temperate soils with different contamination profiles displayed varying levels of cold survivability.