Background Petroleum pollution caused by accidents in petroleum production and transportation will change soil physical and chemical properties, resulting in soil erosion and serious damage to the ecological environment. Phragmites australis is a plant with strong stress resistance, which often is used as a plant material for ecological restoration. It plays an important role in resistance to stress through interaction with rhizosphere bacterial community. Petroleum pollution has a significant influence on the structure and diversity of rhizosphere bacterial community, which may be one of the important factors hindering the growth and development of P. australis in petroleum contaminated soil.
Methods In order to reveal the effects of different concentrations of petroleum pollution on soil and rhizosphere bacterial community of P. australis, soil samples and P. australis rhizomes were collected from Zhalong wetland. P. australis rhizomes planted in soil which had used to simulate mild (3 g/kg), moderate (6 g/kg), and severe (12 g/kg) petroleum pollution. Cultured for 60 d, then soil ammonium nitrogen, available phosphorus, available potassium, and organic matter were measured. The community abundance and composition of the P. australis rhizosphere bacteria under different soil petroleum treatments were detected by high-throughput sequencing and bioinformatics method.
Results Petroleum pollution significantly increased the content of ammonium nitrogen, available phosphorus and organic matter in soil, respectively by 41%, 121% and 141%, but had no significant effect on soil pH value and available potassium. The high-throughput sequencing showed that P. australis rhizosphere soil contained 33 phyla and 111 genera of bacteria, of which Proteobacteria was the dominant bacterium with a proportion from 37.31%-46.6%. There were 23 genera of dominant bacteria (relative abundance >1%), of which Pseudomonas and Hydrogenophaga was the dominant genus that demonstrated good adaptability to petroleum pollution. The bacteria diversity was the lowest in the slight polluted soil, and the highest in the severe polluted soil. Petroleum pollution promoted the growth of Pseudomonas and Hydrogenophaga, and inhibited the growth of Exiguobacterium, Rhodoligotrophos, Citrobacter, Aridibacter, Azoarcus, Gp21, and Mongoliicoccus. Slight petroleum pollution promoted the growth of Desulfuromonas and Bellilinea, and high petroleum pollution inhibits its growth.
Conculsions Petroleum pollution changed soil nutrient content and had a significant effect on bacterial community structure and diversity in the rhizosphere soil of P. australis.
DownLoad: