内蒙古冷凉地区秸秆发酵中微生物群落动态演替与功能协作网络

Dynamic succession and functional collaboration network of microbial communities in straw fermentation in cool areas of Inner Mongolia

摘要:

背景 内蒙古冷凉地区低温限制了玉米秸秆的微生物降解效能，尽管存在多样的低温菌群，但其演替规律与功能仍未知。目的 探究低温(15 ℃)发酵条件下玉米秸秆微生物群落的演替规律与功能特性，揭示细菌与真菌的相互作用机制，为秸秆资源化利用及低温菌剂开发提供理论支撑。方法 构建低温发酵体系，分阶段(SD1-SD4，每隔15 d)采集样本，结合Illumina NovaSeq 6000分析细菌与真菌群落多样性、组成及互作网络，运用线性判别分析效应量(linear discriminant analysis effect size, LEfSe)和相关性网络识别关键功能菌群。结果 细菌特有OTU数随发酵时间延长而逐渐增加，而真菌呈现“降低-增加-降低”趋势。细菌优势门假单胞菌门(Pseudomonadota)、拟杆菌门(Bacteroidota)和放线菌门(Actinomycetota)的相对丰度呈“先降后升”趋势，拟杆菌门在初期占优势，后放线菌门显著富集；真菌群落以子囊菌门(Ascomycota)和接合菌门(Zygomycota)为主。属水平上，鞘氨醇杆菌属(Sphingobacterium)、肠杆菌属(Enterobacter)和罗河杆菌属(Rhodanobacter)在不同阶段主导细菌群落，暗色丝孢菌属(Phaeoacremonium)、嗜热菌属(Mycothermus)和镰刀菌属(Fusarium)呈现真菌群落的阶段性演替。LEfSe分析显示，绿弯菌门(Chloroflexota)和棒囊壳属(Corynascus)是SD3区别于其他阶段的关键功能菌。该复合菌系发酵物提高抗氧化酶活性，增强玉米幼苗耐盐碱胁迫能力。结论 发酵过程中微生物群落呈现显著的阶段演替，细菌与真菌通过功能接力模式形成协同效应，促进冷凉地区秸秆发酵进程。

Abstract:

Background The low temperature in Inner Mongolia cool regions constrains the microbial degradation efficiency of maize straw. Although diverse cool adapted microbial communities are present, their succession patterns and functions roles remain unclear.Objective We investigated the succession patterns and functional characteristics of microbial communities in maize straw under low-temperature (15 ℃) fermentation conditions, aiming to reveal the interaction mechanisms between bacteria and fungi and provide theoretical support for the utilization of straw resources and the development of low-temperature microbial agents.Methods We constructed the low-temperature fermentation system and collected samples at stages (SD1-SD4, every 15 days). Illumina NovaSeq 6000 was employed to analyze the diversity, composition, and interaction networks of bacterial and fungal communities. Linear discriminant analysis effect size (LEfSe) and correlation networks were used to identify key functional microbial groups.Results The number of bacterium-specific OTUs gradually increased over fermentation time, while fungus-specific OTUs showed a “decrease-increase-decrease” trend. The relative abundance of Pseudomonadota, Bacteroidota, and Actinomycetota exhibited a “decrease-increase” trend. Bacteroidota was dominant at the early stage, followed by significant enrichment of Actinomycetota. The fungal community was dominated by Ascomycota and Zygomycota. At the genus level, Sphingobacterium, Enterobacter, and Rhodanobacter were the dominant bacteria at different stages, while Phaeoacremonium, Mycothermus, and Fusarium exhibited stage-specific succession within the fungal community. LEfSe results showed that Chloroflexota and Corynascus were the key functional bacteria that distinguished SD3 from other stages. The fermentation products of the compound microbial system increased the activity of antioxidant enzymes and enhanced the saline-alkali stress tolerance of maize seedlings.Conclusion During fermentation, the microbial community displayed significant staged succession, and bacteria and fungi formed synergistic effects through the functional relay mode to promote the straw fermentation process in cool areas.