Biodegradetion Of Oil Contaminated Soil And The Influnce Of Biodegradation On Soil Bacteial Community Diversity

In recent years, oil had been the core of the energy and economy, but it also caused serous soil pollution. It was important to established an efficient, economic bioremediation method of oil contaminated soil. The Next-generation sequencing technology can been used to research the influence of biodegradation of oil contaminated soil on the soil bacterial community diversity and the interactions among microbial populations. It was instructive and meaningful to the biodegradation ofl oil contaminated soil in field scale.To select the microorganism with the high capacity to degrade the crude oil, nine fungi strains were isolated from the soil contaminated by the crude oil using the plate dilution method. Based on morphological, physio-biochemical characteristics and the internal transcribed spacer (ITS) sequencing, four stains belonged to Fusarium sp., two stains belonged to Aspergillus sp., and the others were respectively identified as Pseudallescheria sp., Eupenicillium sp. and Beauveria sp..Factors influencing the biodegradation of oil contaminated soil were tested including temperature using electric heating, organic matter, surfactant, oxygen and nine fungi selected. The crud oil removal rates (CORR) of treatments with nine fungi was higher than those without the fungi after28d, that meant the fungi could increase CORR.Most of CORRs of all treatments were detected in0-14d, and CORRs of treatments NO.1and NO.2were also higher in15-18d at20℃. CORRs of treatment NO.1to NO.4and NO.13to NO.18were higher in0-14d, but CORRs of other treatments and CK were exactly same in two periods at25℃. The result at30℃were not the same at25℃. CORRs of some treatments were higher in15-28d such as CK, NO.1, NO.2,NO.13, NO.14,NO.15and NO.16, and the higher CORRs of others were discovered in0-14d at30℃.The CORR at25℃was the highest (74.80%) after28d, and the CORR at30℃was the lowest (49.43%). At same temperature, organic matter and oxygen had a strong influence on CORR, and the difference was significant among the influence of the surfactants on CORR at20℃and25℃, but it was not significant at30℃. When there were the same surfactant in the treatments, temperature, organic matter and oxygen had a strong influence on CORR. CORR was the highest at25℃when it added Tween80or no surfactant, but it was highest at30℃when SDS was used. CORR of the treatments used corn cob was the highest when no surfactant was added, and CORR of the treatments used organic fertilizer was the highest when Tween80or SDS was added. CORRs of the treatments mixed in the same organic matter were the highest at25℃. Temperature, organic matter and surfactant had a strong influence on CORRs of the treatments with the same oxygen level, the highest CORRs were detected at25 ℃and in the treatments mixed organic fertilizer. It was found in the treatment without surfactant when soil didn’t add H2O2, or the treatments with SDS when H2O2was added.According to the CORRs, the best biodegradable method of oil contaminated soil in alpine region was treatment S1W1O1:added oil-degrading fungi, Tween80, organic fertilizer and H2O2, CORR was81.46%after28d.Diversity of soil bacteria communities were explored by pyrosequencing analyses of thirteen samples based on CORR and other factors. The thirteen samples were grouped into two clusters according to the relative abundance of operational taxonomic units (OTUs) for16S rRNA gene of bacteria. Samples J17,J25,J27,J28,J29and J30were clustered each other. Sample J1,J2,J8,J11,J12,J21and J22were gathered to a cluster. All sequences observed from thirteen samples belonged to29phyla. And Proteobacteria, Actinobacteria and Bacteroidetes were the most dominant populations in almost all of samples (at phylum level), whereas the preponderant community occurred shifted among the samples. And α-Proteobacteria、β-Proteobacteria、γ-Proteobacteria and Actinobacteria were the most dominant populations at class level, adn the number of y-Proteobacteria bacteria varied greatly, there existed significant positive correlations between CORR and the number of y-Proteobacteria bacteria. Most of the dominant genus identified by the16S rRNA gene sequences from thirteen samples could degraded petroleum hydrocarbons, such as Achromobacter sp.、Acinetobacter sp.、 Arthrobacter sp.、 Bacillus sp.、Brevundimonas sp.、Devosia sp.、Flexibacter sp.、 Gordonia sp.、Nocardia sp.、Parapedobacter sp.、Pseudomonas sp. and Sphingomonas sp., other genus had more properties such as producing bio surfactant and oil desulfurization(Rhodpcpccus sp.), reducing nitrate (Paracoccus sp.), degradating pesticides (Phenylobacterium sp.、Sphingobium sp.、Sphingopyxis sp.)and associating with humic acid. Correlation analysis showed that there existed significant negative correlations between CORR and the number of degraded petroleum hydrocarbons genus. The numbers of Candidatus Chloracidobacterium sp.bacteria were lower in the samples with poor oxygen conditions and low organic matter content.