原始森林土壤秸秆降解微生物组的历史地理气候驱动力

Deciphering the driving force of straw-decomposing microbiomes in two native forest soils under biogeographically contrasting conditions

摘要:

【目的】 针对相距3 860 km的热带(年均温25 ℃)和寒温带(年均温−2 ℃)原始森林土壤，研究历史地理气候显著差异条件下秸秆降解微生物群落的适应规律。【方法】 设置低温(10 ℃)、高温(35 ℃)和高低温交叉锻炼(10 ℃/35 ℃)，连续12周传代并通过16S rRNA基因测序分析秸秆降解微生物组群落组成。【结果】 10 ℃下寒温带长白山土壤富集菌群的秸秆降解率(15.5%)更高；35 ℃下则是海南土壤富集菌群的降解率(33.1%)更高。线性判别分析效应大小(linear discriminant analysis effect size, LEfSe)差异分析显示，针对寒温带长白山原始森林土壤，在微生物属水平上，10 ℃条件下12周传代富集得到的秸秆降解优势属包括杜擀氏菌属(Duganella)、土地杆菌属(Pedobacter)、紫色杆菌属(Janthinobacterium)和沙雷氏菌属(Serratia)；35 ℃条件下秸秆降解富集物中优势属包括类芽孢杆菌属(Paenibacillus)和罗河杆菌属(Rhodanobacter)；而10 ℃/35 ℃条件下寡养单胞菌属(Stenotrophomonas)、伯克霍尔德氏菌属(Burkholderia)与无色杆菌属(Achromobacter)是秸秆降解优势类群。针对热带海南原始森林土壤，10 ℃条件下富集的秸秆降解优势属包括假单胞菌属(Pseudomonas)、不动杆菌属(Acinetobacter)和黄杆菌属(Flavobacterium)；35 ℃条件下优势属为贪铜菌属(Cupriavidus)；而10 ℃/35 ℃条件下肠杆菌属(Enterobacter)和科恩氏菌属(Cohnella)是优势属。【结论】 热带和寒温带的巨大温度差异，可能是原始森林土壤中秸秆降解微生物群落构建的重要驱动力，这些特征微生物类群为定向发掘东北寒区和南方热带土壤中高效降解秸秆的微生物资源提供了科学依据。

Abstract:

[Objective] To investigate the acclimation mechanisms of straw-decomposing microbiomes in response to historically different climate conditions as characterized by extreme temperature distinction, we collected two native forest soil samples from the tropical (annual mean temperature: 25 ℃) and cold-temperate (annual mean temperature: −2 ℃) zones at a distance of 3 860 km. [Methods] Microcosm incubation was conducted at a low temperature (10 ℃), a high temperature (35 ℃), and alternated high and low temperatures (10 ℃/35 ℃). The two native forest soil samples were inoculated for targeted cultivation of straw-decomposing microbiomes. After 12 consecutive weeks of passage, 16S rRNA gene sequencing was carried out to analyze the microbial community composition. [Results] At 10 ℃, higher straw decomposition rate was observed in the forest soil from Changbai Mountain in the cold-temperate zone (15.5%) than that from the tropical zone. At 35 ℃, the decomposition rate in the soil from Sanya in the tropical zone (33.1%) was higher than that from Changbai Mountain The results of linear discriminant analysis effect size (LEfSe) showed that the dominant straw-decomposing genera included Duganella, Pedobacter, Janthinobacterium, and Serratia after 12 weeks of enrichment at 10 ℃ with the forest soil from Changbai Mountain. The dominant genera were Paenibacillus and Rhodanobacter after enrichment at 35 ℃, and Stenotrophomonas, Burkholderia, and Achromobacter after enrichment at 10 ℃/35 ℃. As for the forest soil from the tropical zone, the enriched dominant genera were Pseudomonas, Acinetobacter, and Flavobacterium at 10 ℃, Cupriavidus at 35 ℃, and Enterobacter and Cohnella at 10 ℃/35 ℃. [Conclusion] This study revealed the indicator microbial species for straw decomposition at different temperatures in native forest soils from geographically highly distinct regions with a 3 860 km distance. The results suggest that temperature could have likely played a pivotal role in shaping the microbiomes for straw decomposition. The findings provide a scientific basis for mining the straw-decomposing microbial resources in the cold zone in northeast China and the tropical zone in south China.