Enrichment of pendimethalin-degrading microbial consortia and their succession

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.