Pyrene dissipation potential varies with soil type and associated bacterial community changes

Understanding the relationship between polycyclic aromatic hydrocarbon (PAH) dissipation potential in different soils and the bacterial community changes is of great importance for bioremediation and ecological evaluation. Soil microcosms were constructed with four different types of soils, including Anthrosol (Ant), Black soil (Black), Fluvo-aquic soil (Flu), and Red soil (Red), by spiking with pyrene at three concentrations (5, 30, and 70 mg kg−1). Real-time PCR and Illumina sequencing were employed to examine the bacterial community changes. The results showed that the pyrene dissipation rate differed with soil type. The fastest pyrene dissipation was observed in Ant soil: greater than 90% reduction was achieved by day 14 at higher pyrene dosages (30 and 70 mg kg−1) and no lag time existed before onset of pyrene dissipation at all spiked dosages. A 7-day and 14-day lag time was needed in Black and Flu soils, respectively before pyrene dissipation at pyrene concentration of 70 mg kg−1, more than 90% reduction of pyrene could still be achieved by day 21 for the Black soil and by day 42 for the Flu soil at all pyrene dosages. The evident reduction of pyrene in Ant, Black, and Flu soils was significantly correlated (r = 0.847-0.914; P < 0.05) with the increase of the pyrene dioxygenase gene (nidA) abundance. Moreover, the enrichment of the specific bacterial phylotypes at the phylum/class and genus level was strongest in the Ant soil but was relatively lower in the Black and Flu soils. However, pyrene reduction didn't occur in the Red soil during the entire incubation (42 days). This poor degradation ability was associated with the stability or decrease of the nidA gene quantity and very different types of the enriched genera from that in Ant, Black, and Flu soils. This work is helpful for understanding of the mechanisms that led to the contrasting pyrene fates in different types of soils from the view point of microbiology.