Impact of common sample pre-treatments on key soil microbial properties
Impact of common sample pre-treatments on key soil microbial properties
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DOI：
10.1016/j.soilbio.2021.108321
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发表时间：
2021-06-06
影响因子：
9.7
通讯作者：
Poeplau, Christopher
中科院分区：
文献类型：
--
作者：
Schroeder, Julia;Kammann, Lisa;Poeplau, Christopher
在分析之前对土壤样品进行预处理被认为会影响微生物活性和群落参数，但建议存在分歧，没有最佳做法或标准化的实验室协议。对于微生物碳利用效率（CUE）作为分配给微生物的碳与总代谢碳的比率参数，样品预处理的影响是不可预测的，因为微生物代谢的基本参数可能会受到不同的影响。在处理或土地利用比较中，重要的是要知道土壤是否受到预处理的类似影响。基于5个不同的配对网站（每个与农田和森林），6个常见的预处理的18 O-CUE和相关参数，即呼吸速率，土壤微生物生物量C，提取的总DNA，真菌，细菌和古菌的丰度估计的影响进行了评估。六种常见的预处理是：（i）现场新鲜土壤样品的立即分析，以及（ii）现场新鲜，（iii）风干，（iv）烘干（40 ℃），（v）在-20 ℃冷冻和（vi）原位冷冻（干冰和随后的液氮）的土壤样品14天预孵育后的分析。实验揭示了两个主要发现。第一个是，预孵育14天的效果最明显，降低微生物呼吸速率，生长速率和微生物生物量C之间的平均28%和63%，与现场新鲜样品相比，这表明在容易获得的基板上的微生物活性的减少的影响。第二个发现是，即使经过14天的预孵育，干燥和再润湿也会导致森林土壤样品中的微生物呼吸速率增加64 +/- 53%（风干）和86 +/- 65%（烘干），这被称为Birch效应。然而，CUE作为一个比率参数被发现是不受样品预处理，只有轻微的变化后，14天的预孵育。预处理（包括预孵育）影响农田和森林样品类似，有一个例外：真菌的估计丰度增加，只有干燥和再湿润的森林土壤。这表明，干燥的农田土壤可能产生适当的社区数据，而森林土壤对土壤干燥的反应更为复杂。结果表明，无论土壤样品是干燥复湿、冻融还是新鲜储存，都可以获得CUE值。
Pre-treatment of soil samples prior to analysis is acknowledged to affect microbial activity and community parameters, but recommendations are diverging and there are no best-practice or standardised laboratory protocols. For the microbial carbon use efficiency (CUE) as a ratio parameter of C allocated to anabolism over total metabolised C, the effects of sample pre-treatment are unpredictable because the underlying parameters of microbial metabolism may be affected differently. In treatment or land use comparisons, it is important to know whether soils are affected in a similar way by pre-treatment. Based on five different paired sites (each with cropland and forest), the effects of six common pre-treatments were evaluated on 18O-CUE and associated parameters, i.e. respiration rate, soil microbial biomass C, total DNA extracted, and estimated abundances of fungi, bacteria and archaea. The six common pre-treatments were: (i) immediate analysis of field-fresh soil samples, and analysis following 14 d pre-incubation of soil samples that were (ii) field-fresh, (iii) air-dried, (iv) oven-dried (40 degrees C), (v) frozen at -20 degrees C and (vi) frozen in-situ (dry ice and subsequently liquid N2). The experiment revealed two main findings. The first was that pre-incubation of 14 d had the most pronounced effect and reduced microbial respiration rate, growth rate and microbial biomass C by between 28% and 63% on average compared with field-fresh samples, suggesting an impact of the reduction in readily available substrates on microbial activity. The second finding was that even after 14 days of pre-incubation, drying & rewetting caused an increase in the microbial respiration rate in forest soil samples of 64 +/- 53% (air-drying) and 86 +/- 65% (oven-drying), known as the Birch effect. However, CUE as a ratio parameter was found to be unaffected by sample pre-treatment, with only minor changes after 14 d of pre-incubation. Pre-treatment (including pre-incubation) affected cropland and forest samples similarly, with one exception: the estimated abundance of fungi increased only with drying & rewetting in forest soils. This suggests that dried cropland soils could potentially yield appropriate community data, while forest soils respond to soil drying in a more complex way. It was concluded that CUE values can be derived from soil samples regardless of whether they were dried & rewetted, frozen & thawed, or stored fresh.