高通量测序解析多环芳烃污染盐碱土壤翅碱蓬根际微生物群落多样性

Diversity of bacterial community in Suaeda roots rhizosphere growth in PAHs-contaminated saline soil estimated by high throughput sequencing method

摘要:

【目的】以多环芳烃(PAHs)污染盐碱土壤为对象，分析比较翅碱蓬根际与非根际土壤细菌群落多样性，为植物-微生物联合修复PAHs污染盐碱土壤提供依据。【方法】在胜利油田油井附近采集翅碱蓬根际土壤和无翅碱蓬生长区域的裸地表层土壤，基于高通量测序技术分析样品中微生物群落结构，并进一步运用Real-time PCR解析土壤中PAHs双加氧酶基因丰度。【结果】翅碱蓬根际土壤盐含量为22.51 g/kg，明显低于裸地土壤的40.03 g/kg，土壤pH值差别不大，分别为8.20和8.22；根际土壤有机质和总氮含量分别为24.41 g/kg和1.59 g/kg，C/N值为15，裸地土壤有机质和总氮含量分别为18.80 g/kg和0.71 g/kg，C/N值为26；高通量测序得到根际和裸地土壤样品优质序列分别为53 854条和30 312条，在97%相似水平下，根际土壤样品所得OTU数、Chao 1指数和ACE指数分别为5 934、11 461和15 555，分别高于裸地土壤对应指数的值(4 262、8 262、11 186)，序列分析结果显示，根际土壤包含细菌32门758属，多于裸地土样28门676属，翅碱蓬根际土壤群落结构多样性均高于裸地土壤；PAHs污染盐碱土壤中存在丰富的微生物资源，有Thioalkalispira、Halothiobacillus、Thiohalophilus等多种嗜盐碱或耐盐碱微生物，并在根际土壤中检测到了PAHs双加氧酶基因(PAH-RHDα)。【结论】Thioalkalispira、Halothiobacillus、Thiohalophilus等嗜盐碱或耐盐碱微生物是胜利油田PAHs污染盐碱土壤中的优势菌属；翅碱蓬能有效降低根际土壤盐含量并改善C/N值，增加微生物群落结构多样性，提高PAHs关键功能基因的丰度，有助于促进嗜盐碱PAHs降解微生物在PAHs污染盐碱土壤的生物修复中发挥作用。

Abstract:

[Objective] Analysis and comparison of the bacterial community diversity in Suaeda roots rhizosphere and non-rhizosphere polycyclic aromatic hydrocarbons (PAHs) contaminated saline soil to provide the basis for plant-microbial remediation of PAHs contaminated saline soil. [Methods] Soil samples were collected from Suaeda roots rhizosphere and non rhizosphere at an oil well site in Shengli oil field. Bacterial community structures were analyzed by high throughput sequencing, and further the abundance of PAH-ring hydroxylating dioxygenase (PAH-RHDα) genes in soil was detected by Real-time PCR. [Results] The salt content of Suaeda roots rhizosphere soil is 22.51 g/kg, which is significantly lower than the salt content (40.03 g/kg) in non rhizosphere soil. The pH of rhizosphere and non-rhizosphere soil were basically the same, which were 8.20 and 8.22. The organic matter content and total nitrogen content of rhizosphere soil is 24.41 g/kg and 1.59 g/kg, respectively, which made C/N 15. These contents of non rhizosphere soil are 18.80 g/kg and 0.71 g/kg, respectively, which made C/N 26. The bacterial communities were analyzed and at least 53 854 and 30 312 sequencing were obtained for rhizosphere and non-rhizosphere soil samples. At 97% similarity level, the OTU number, Chao 1 index and ACE index are 5 934, 11 461 and 15 555 respectively in rhizosphere soil sample, which are higher than the index values in non-rhizosphere soil (4 262, 8 262 and 11 186). The rhizosphere soil contains 32 phyla and 758 genera of bacteria, more than those in the bare soil (28 phyla and 676 genera). Bacteria abundance and diversity of Suaeda roots rhizosphere soil were higher than that of the non-rhizosphere soil. There are rich resources of haloalkaliphilic microorganisms in PAHs-contaminated saline alkali soil, such as Thioalkalispira, Halothiobacillus, Thiohalophilus, and the PAH-RHDα genes were detected in the rhizosphere soil. [Conclusion] Haloalkaliphilic bacteria such as Thioalkalispira, Halothiobacillus, and Thiohalophilus were the dominant microorganism in PAHs-contaminated saline alkali soil. Suaeda can reduce the salt content and improve the C/N value of rhizosphere soil effectively, simultaneously increase the diversity of microbial communities structure and the abundance of PAH-RHDα genes. Therefore, Suaeda was beneficial to promote halophilic PAHs degrading microorganisms play a role in bioremediation of PAHs-contaminated saline-alkali soil.