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| Application of immobilization technology of cold tolerance microorganisms in the remediation of polycyclic aromatic hydrocarbons in freeze-thaw soil |
| Received:January 09, 2019 |
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| KeyWord:immobilized mixed strains;soil;microbial diversity;kinetics;low temperature freezing and thawing |
| Author Name | Affiliation | E-mail | | PU Yu | School of Environmental Science, Liaoning University, Shenyang 110036, China | | | SU Dan | School of Environmental Science, Liaoning University, Shenyang 110036, China | sudan1980@126.com | | WANG Xin | Key Laboratory of Regional Environment and EcoRemediation, Ministry of Education, Shenyang University, Shenyang 110044, China | wx1979@126.com | | WANG Tian-jie | School of Environmental Science, Liaoning University, Shenyang 110036, China | | | LIU Wei | School of Environmental Science, Liaoning University, Shenyang 110036, China | |
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| Abstract: |
| A bacterial(Pseudomonas sp.)and fungal(Mortierella alpina)strain were screened from oil-contaminated frozen-thawed soil, and the mixture of microorganisms was immobilized using corncobs as carriers to study the bio-augmented remediation of phenanthrene (Phe)and benzo[b]fluoran(BbF)-contaminated soil by the immobilized mixed bacteria under a low temperature freeze-thaw environment. The degradation dynamics of Phe and BbF in soil were analyzed using a high-performance liquid chromatography(HPLC)method, and the results were fitted to the Michaelis-Menton and Monod dynamic models, while changes of the microbial community were analyzed using high-throughput sequencing technology. The results showed that before the bio-augmented treatment, the concentrations of Phe and BbF in freeze-thaw soil were(105.4±4.8)and(6.12±1.1)mg·kg-1, respectively. After a 60 d remediation experiment,(56.62±3.21)% and (38.21±1.82)% of Phe and BbF, respectively, in the soil could be removed by the immobilized mixed bacteria, which displayed a better resistance and degradation ability to the freeze-thaw environment than did the free bacteria. In the remediation test, the pre-stabilization degradation rate was higher than the stable degradation rate was. The addition of immobilized mixed bacteria significantly increased the degradation rate of Phe and BbF to 2.02 d-1 and 0.65 d-1, respectively, while the half-life of degradation was shortened to 50.17 d-1 and 82.12 d-1, respectively. In the bio-augmented remediation process, the microbial community composition and diversity in soil were changed, and the diversity and uniformity of bacteria decreased. The degradation rate of polycyclic aromatic hydrocarbons(PAHs)was negatively correlated with community diversity and uniformity of bacteria. Proteobacteria and Mortierellomycota became the dominant phyla with a relative abundance of 80.03% and 81.15%, respectively, while Pseudomonas SDR4 and Mortierella alpina JDR7 became the dominant genera with a relative abundance of 80.03% and 81.15%, respectively, forming a degradation system consisting of a significant fungal-bacterial symbiotic dominant strain, which significantly improved the remediation efficiency of PAH pollution in low temperature soil. The immobilized strains could be widely used in bioremediation of soil PAH pollution in freeze-thaw environments. |
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