BACKGROUND Methanol is the second most abundant volatile organic compound in the atmosphere, with the majority produced as a metabolic by-product during plant growth. There is a large disparity between the estimated amount of methanol produced by plants and the amount which escapes to the atmosphere. This may be due to utilisation of methanol by plant-associated methanol-consuming bacteria (methylotrophs). The use of molecular probes has previously been effective in characterising the diversity of methylotrophs within the environment. Here, we developed and applied molecular probes in combination with stable isotope probing to identify the diversity, abundance and activity of methylotrophs in bulk and in plant-associated soils. RESULTS Application of probes for methanol dehydrogenase genes (mxaF, xoxF, mdh2) in bulk and plant-associated soils revealed high levels of diversity of methylotrophic bacteria within the bulk soil, including Hyphomicrobium, Methylobacterium and members of the Comamonadaceae. The community of methylotrophic bacteria captured by this sequencing approach changed following plant growth. This shift in methylotrophic diversity was corroborated by identification of the active methylotrophs present in the soils by DNA stable isotope probing using 13C-labelled methanol. Sequencing of the 16S rRNA genes and construction of metagenomes from the 13C-labelled DNA revealed members of the Methylophilaceae as highly abundant and active in all soils examined. There was greater diversity of active members of the Methylophilaceae and Comamonadaceae and of the genus Methylobacterium in plant-associated soils compared to the bulk soil. Incubating growing pea plants in a 13CO2 atmosphere revealed that several genera of methylotrophs, as well as heterotrophic genera within the Actinomycetales, assimilated plant exudates in the pea rhizosphere. CONCLUSION In this study, we show that plant growth has a major impact on both the diversity and the activity of methanol-utilising methylotrophs in the soil environment, and thus, the study contributes significantly to efforts to balance the terrestrial methanol and carbon cycle. Video abstract.

中文翻译：

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植物对土壤中甲基营养生物的多样性和活性的影响。

背景技术甲醇是大气中第二丰富的挥发性有机化合物，其中大部分是植物生长过程中的代谢副产物。估计植物产生的甲醇量与逃逸到大气中的甲醇量之间存在很大差异。这可能是由于植物相关的消耗甲醇的细菌（甲基营养菌）对甲醇的利用。分子探针的使用先前已在表征环境中甲基营养生物的多样性方面有效。在这里，我们开发和应用分子探针与稳定同位素探测相结合，以鉴定散装和与植物相关的土壤中甲基营养菌的多样性，丰度和活性。结果甲醇脱氢酶基因（mxaF，xoxF，mdh2）在大块土壤和与植物相关的土壤中显示，大块土壤中的甲基营养细菌具有很高的多样性，包括嗜氧菌，甲基杆菌和Comamonadaceae成员。通过这种测序方法捕获的甲基营养细菌群落随着植物的生长而改变。通过使用13C标记的甲醇进行DNA稳定同位素探测，鉴定土壤中存在的活性甲基营养菌，从而证实了甲基营养菌多样性的这种变化。16S rRNA基因的测序和由13C标记的DNA的元基因组的构建表明，在所有检查过的土壤中，嗜甲基菌科成员都非常丰富和活跃。与散装土壤相比，与植物相关的土壤中的嗜甲基菌科和昏迷科的活性成员以及甲基杆菌属的活性成员的多样性更大。在13CO2气氛中孵育正在生长的豌豆植物，发现放线菌属中的几个甲基营养菌属和异养属属吸收了豌豆根际中的植物渗出物。结论在这项研究中，我们表明植物的生长对土壤环境中利用甲醇的甲基营养生物的多样性和活性都具有重大影响，因此，该研究为平衡陆地甲醇和碳循环做出了重要贡献。录像摘要。我们表明，植物的生长对土壤环境中利用甲醇的甲基营养生物的多样性和活性均具有重大影响，因此，该研究对平衡陆地甲醇和碳循环的工作做出了重要贡献。录像摘要。我们表明，植物的生长对土壤环境中利用甲醇的甲基营养生物的多样性和活性均具有重大影响，因此，该研究对平衡陆地甲醇和碳循环的工作做出了重要贡献。录像摘要。