Smith Montana L, Weitz Karl K, Thompson Allison M, Jansson Janet K, Hofmockel Kirsten S, Lipton Mary S
Pacific Northwest National Laboratory, Richland, WA 99354, USA.
Microorganisms. 2023 Oct 26;11(11):2630. doi: 10.3390/microorganisms11112630.
Microbial response to changing environmental factors influences the fate of soil organic carbon, and drought has been shown to affect microbial metabolism and respiration. We hypothesized that the access of microbes to different carbon pools in response to dry-rewet events occurs sequentially at different rates. We amended desiccated soils with C-labeled glucose and measured the rates of CO and CO respiration in real time after rewetting. Using these differentiated CO and CO respiration rate soils after rewetting, we were able to deduce when microbes are accessing different pools of carbon. Immediately upon rewetting, respiration of CO occurred first, with negligible CO respiration. Appreciable metabolism and respiration of the added C glucose did not occur until 15 min after rewetting. We conclude that, while all carbon pools are being accessed in the first 9 h after rewetting, the rate and timing at which new and existing carbon pools are being accessed varies. Within this study, using stable isotope-labeled substrates to discern which carbon pools are metabolized first uniquely illustrates how microorganisms access different carbon pools which has implications into understanding how carbon metabolism can further affect climate, carbon sequestration, and soil health.
微生物对不断变化的环境因素的响应影响着土壤有机碳的归宿，并且干旱已被证明会影响微生物的代谢和呼吸作用。我们假设，微生物在干湿交替事件中对不同碳库的利用是以不同速率依次发生的。我们用碳标记的葡萄糖对干燥土壤进行修正，并在重新湿润后实时测量一氧化碳和二氧化碳的呼吸速率。利用重新湿润后这些具有不同一氧化碳和二氧化碳呼吸速率的土壤，我们能够推断出微生物何时利用不同的碳库。重新湿润后立即发生的是一氧化碳的呼吸，二氧化碳的呼吸可忽略不计。直到重新湿润15分钟后，添加的碳葡萄糖才出现明显的代谢和呼吸。我们得出结论，虽然在重新湿润后的前9小时内所有碳库都被利用，但利用新的和现有的碳库的速率和时间各不相同。在本研究中，使用稳定同位素标记的底物来辨别哪些碳库首先被代谢，独特地说明了微生物如何利用不同的碳库，这对于理解碳代谢如何进一步影响气候、碳固存和土壤健康具有重要意义。
