Microbial Community Structure And Distribution Characteristics In Oil Contaminated Soil

This study aims to investigate the phylogenetic diversity and community structure of bacteria in petroleum contaminated soils from Karamay oilfield, and to analyze the relationship between the community variation and the environment parameters, to provide a reference for bioremediation of petroleum contaminated soils. As 16 S r RNA gene for target, the bacteria microbial communities were analyzed by 16 S r RNA clone library and high-throughput sequencing respectively. We collected the samples from the petroleum contaminated soils in 5 cm, 20 cm, 50 cm depth layers, and measured the environment parameters subsequently; We constructed three 16 S r RNA gene clone libraries of these soil samples, and then the operation taxonomy units(OTUs) were determined by RFLP method and the representative clones of every OUT were sequenced. The diversity, richness and evenness index of the bacteria communities were calculated by using Biodap software. Neighbour–joining phylogenetic tree was constructed basing on the 16 S r RNA gene sequences of bacteria from Karamay oil field and the references from related environments. Canonial correspondence analysis(CCA) was used to analyze the relationship between the environment parameters and the species by using CANOCO 4.5 software. 16 S r RNA gene clone library also was investigated by Hiseq 2500 sequencing platform. Environment parameters showed that 50 cm layer soil contained the highest amount of total nitrogen(TN) and total phosphorus(TP), while the 20 cm layer soil contained the lowest amount; The 5 cm layer soil contained the highest amount of total organic carbon(TOC), while the 50 cm layer soil contained the lowest amount; Among the three layers, 20 cm layer had the highest diversity and richness of bacteria, while the bacteria in 50 cm layer was the lowest. Phylogenic analyses suggested that the bacteria in the Karamay oilfield could be distributed into five groups at the level of phylum, Cluster I to V, respectively belong to Proteobacteria, Actinobacteria, Firmicute, Bacteroidetes, Planctomycetes. CCA results showed that TN, TP, TOC significantly affected the bacteria community structure, especially, TOC content significantly related to the distribution of Pseudomonas.The results of high-throughput sequencing showed that the three layers of the soil samples contained in the predominant groups of bacteria was roughly same, respectively were Proteobacteria、Actinobacteria、Firmicutes。Three samples of Chao index and Shannon index was larger, and the diversity of 20 cm soil sample was the highest, 5 cm soil sample second, 50 cm soil sheet for low. Three soil samples library coverage above 99%, in this study the library contains most bacteria groups, can fully reflect the sample of the bacterial community structure and diversity.Under the phylum taxonomic level, Proteobacteria was the dominant; under the taxonomic levels of microorganism such as genus, marinobacter accounted for 12%, becoming the most advantage of the soil. CCA results showed that TN, TP, TOC significantly affected the bacteria community structure. What information could 16 S r RNA clone library and high-throughput sequencing gotten respectively were some different in reflecting all of the microbial community of petroleum contaminated soils. Furthermore, as researching for the main microbial community and especially for the dominant microbial community of petroleum contaminated soil there were some similar results gotten by both two methods. The results of Shannon index and Simpon index showed that high-throughput sequencing than clone library can more objective reaction oil pollution true information about the structure of the bacteria in the soil microbial. The petroleum–contaminated soils inhabited abundant of bacteria. The diversity index and spatial distribution of these communities were affected by the environment parameters in the soil.