二甲戊灵降解菌群富集及其微生物群落结构演替

Enrichment of pendimethalin-degrading microbial consortia and their succession

摘要:

二硝基苯胺类农药二甲戊灵作为苗前封闭除草剂，在新疆棉田广泛被用于杂草防控。二甲戊灵化学性质稳定，残留期长，具有生物积累性和生物放大性的特点，其大量使用导致土壤生态系统风险加剧。因此，二甲戊灵残留修复问题受到广泛关注。目的 富集具有二甲戊灵降解能力的微生物菌群，深入研究二甲戊灵胁迫下富集培养过程中微生物群落的演替特征，确定二甲戊灵降解菌群的关键微生物。方法 通过富集传代培养法，将长期受二甲戊灵胁迫的棉田土壤接种至含不同浓度二甲戊灵(0、1.2、12 mg/L)的基础无机盐培养基中，进行连续传代培养。采用高通量测序技术探究二甲戊灵胁迫下微生物群落结构的演替规律。结果 通过富集培养获得了2个具有二甲戊灵降解功能的微生物菌群，其中L4组(低浓度组第4代)在11 d内对1.2 mg/L二甲戊灵的降解率达到100%，H4组(高浓度组第四代)在相同时间内对12 mg/L二甲戊灵的降解率为37.2%。高通量测序分析结果显示，二甲戊灵胁迫显著降低了微生物群落的α多样性，且细菌群落对二甲戊灵胁迫的响应强于真菌群落。二甲戊灵浓度差异显著改变了微生物群落结构。高浓度二甲戊灵胁迫降低了微生物网络的稳定性、复杂性及模块化程度。线性判别分析(linear discriminant analysis effect size, LEfSe)显示，高浓度组细菌群落中的特征类群为无色杆菌属(Achromobacter)、雷夫松氏菌属(Leifsonia)、Candidatus_Nucleicultrix、肠杆菌属(Enterobacter)和金黄杆菌属(Chryseobacterium)；低浓度组的特征类群为甲基营养菌属(Methyloversatilis)、假黄单胞菌属(Pseudoxanthomonas)、屈曲杆菌属(Ancylobacter)、甲基红杆菌属(Methylorubrum)、热单胞菌属(Thermomonas)和假黄色细杆菌属(Pseudoflavitalea)。篮状菌属(Talaromyces)、木霉属(Trichoderma)、副顶孢霉属(Paracremonium)、帚霉属(Scedosporium)和Sarocladium为高浓度组真菌群落的特征类群。基于PICRUSt2分析发现，二甲戊灵添加组显著富集了与降解相关的功能途径。属水平物种与二甲戊灵降解相关性分析结果显示，在低浓度组中，Methylorubrum、生丝微菌属(Hyphomicrobium)、微杆菌属(Microbacterium)、红假单胞菌属(Rhodopseudomonas)和镰孢菌属(Fusarium)与二甲戊灵降解呈正相关；在高浓度组中，Hyphomicrobium、Leifsonia、Rhodopseudomonas、Talaromyces和Trichoderma与二甲戊灵降解呈正相关。结论 通过不同浓度二甲戊灵胁迫富集获得到了2个具有二甲戊灵降解能力的天然微生物群落。结合高通量测序技术，探究了二甲戊灵降解菌群富集过程中微生物群落的演替规律，初步确定了二甲戊灵降解菌群的关键微生物，为二甲戊灵高效微生物降解菌株的筛选提供了理论依据。

关键词:二甲戊灵;微生物群落;污染物降解

Abstract:

The dinitroaniline herbicide pendimethalin, as a pre-emergent herbicide, is widely employed for weed control in cotton fields across Xinjiang. Characterized by chemical stability, prolonged residual activity, bioaccumulative potential, and biomagnification, it is extensively applied in agricultural practice, leading to increased risks to soil ecosystems. Accordingly, the removal of pendimethalin residues has garnered increasing attention.Objective To enrich the microbial consortia with pendimethalin-degrading ability, study succession characteristics of microbial consortia during the enrichment culture process under pendimethalin stress, and identify the key microorganisms involved in pendimethalin degradation.Methods The cotton field soil under long-term pendimethalin stress was inoculated into MSM media with pendimethalin at 0, 1.2, and 12 mg/L, respectively. The succession of the microbial consortium structure under pendimethalin stress was investigated by high-throughput sequencing.Results Two microbial consortia capable of degrading pendimethalin were enriched. Among them, L4 (low-concentration group) achieved a degradation rate of 100% for 1.2 mg/L pendimethalin within 11 days, while H4 (high concentration group) showed a degradation rate of 37.2% for 12 mg/L pendimethalin over the same period. The alpha diversity of microbial consortia was considerably decreased by pendimethalin stress, and the bacteria responded to the stress more strongly than fungi. The microbial consortium structure varied with different concentrations of pendimethalin. The network stability, complexity, and modularity were diminished by pendimethalin stress. Linear discriminant analysis effect size (LEfSe) results showed that the specific bacterial taxa in the high concentration group were Achromobacter, Leifsonia, Candidatus_Nucleicultrix, Enterobacter, and Chryseobacterium. The specific bacterial taxa in the low concentration group were Methyloversatilis, Pseudoxanthomonas, Ancylobacter, Methylorubrum, Thermomonas, and Pseudoflavitalea. Talaromyces, Trichoderma, Paracremonium, Scedosporium, and Sarocladium were the specific fungal taxa. The PICRUSt2 analysis showed the pendimethalin stress significantly enriched the pathways related to degradation. The correlation analysis between microbial genera and pendimethalin degradation showed that Methylorubrum, Hyphomicrobium, Microbacterium, Rhodopseudomonas, and Fusarium had positive correlations with pendimethalin degradation in the low concentration group. Hyphomicrobium, Leifsonia, Rhodopseudomonas, Talaromyces, and Trichoderma were positively correlated with pendimethalin degradation in the high concentration group.Conclusion Two microbial consortia capable of degrading pendimethalin were successfully obtained through enrichment culture under varying concentrations of pendimethalin. Leveraging high-throughput sequencing, this study systematically explored the succession patterns of microbial consortia under pendimethalin stress. Key functional microorganisms associated with pendimethalin degradation were preliminarily identified. The findings provide a theoretical basis for the targeted screening of efficient microbial strains dedicated to pendimethalin degradation.

Key words:pendimethalin;microbial consortium;pollutant degradation