The variable response of soil microorganisms to trace concentrations of low molecular weight organic substrates of increasing complexity
The variable response of soil microorganisms to trace concentrations of low molecular weight organic substrates of increasing complexity
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DOI：
10.1016/j.soilbio.2013.03.036
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发表时间：
2013-09-01
影响因子：
9.7
通讯作者：
Evershed, R. P.
中科院分区：
文献类型：
--
作者：
Dungait, Jennifer A. J.;Kemmitt, Sarah J.;Evershed, R. P.
与单一低分子量（LMW）有机基质相比，在复杂混合物处理的土壤中观察到CO2呼吸速率升高，并推测更多样化的土壤微生物对日益复杂的LMW有机基质混合物作出反应。为了验证这一假设，将C-13标记的底物（甘氨酸、氨基酸混合物和植物根的水溶性化合物提取物）以15 μ g C g（-1）土壤的量施用于可耕地表层土壤。培养8、24、48、120和240 h后，对土壤进行破坏性取样，并测定革兰氏阴性细菌、革兰氏阳性细菌、放线菌和真菌的生物标志物PLFA的C-13含量。在孵育结束时（120和240 h），除了放线菌外，生物标志物PLFA的浓度没有显著增加。然而，由于16：0和18：0 PLFA的增加，总PLFA浓度发生了显著变化，这不能归因于微生物的特定官能团。C-13掺入到所有微生物组的生物标志物PLFA中在每个时间点都是显著的，但与甘氨酸相比，在施用氨基酸混合物后，在所有微生物组的生物标志物PLFA中测定到更多的C-13。不同生物标志物PLFA中C-13掺入比例的计算表明，随着时间的推移，底物C-13在微生物组之间的路由。这与不同微生物群体的广泛功能生态学（“r”或“K”策略）有关。总之，我们观察到，所有微生物组的响应（检测为C-13掺入）增加了添加更复杂的混合物的低分子量有机底物，但不同的微生物组响应不同的时间。(C)2013爱思唯尔有限公司保留所有权利。
Elevated CO2 respiration rates have been observed in soils treated with complex mixtures versus single low molecular weight (LMW) organic substrates, and it has been postulated that a more diverse range of soil microorganisms responds to increasingly complex mixtures of LMW organic substrates. To test this hypothesis, C-13-labelled substrates (glycine, an amino acid mixture and an extract of water soluble compounds from plant roots) were applied at 15 mu g C g(-1) soil to an arable top soil. The soils were incubated and destructively sampled after 8, 24, 48, 120 and 240 h, and the C-13 content of biomarker PLFA for Gram negative bacteria, Gram positive bacteria, Actinobacteria and fungi was determined. There was no significant increase in the concentration of the biomarker PLFA, apart from Actinobacteria at the end of the incubation (120 and 240 h). However there were significant changes in total PLFA concentration due to increases in the 16:0 and 18:0 PLFA, which cannot be assigned to specific functional groups of microorganisms. C-13 incorporation into the biomarker PLFA of all microbial groups was significant at every time point, but more C-13 was determined in the biomarker PLFA of all microbial groups after the application of the amino acid mixture compared to glycine. Calculations of the proportion of the incorporated of C-13 in the different biomarker PLFA suggested the routing of substrate C-13 between the microbial groups over time. This was related to the broad functional ecology ('r' or 'K' strategy) of the different microbial groups. In conclusion, we observed that the response of all microbial groups (detected as C-13 incorporation) was increased by the addition of more complex mixtures of LMW organic substrates, but that different microbial groups responded differently over time. (C) 2013 Elsevier Ltd. All rights reserved.