摘要
微生物总活性是指在某一时段内微生物所有生命活动的总和,它直接决定着微生物行使生理、生态功能的能力,是微生物学研究的热点,也是难点。迄今为止,还没有建立直接测定微生物总活性的方法,只能用一些相关指标来间接反映它。目前常用的指标主要包括微生物的呼吸速率、生长速率以及胞内RNA含量等。与其它一些基质和环境相比,测定土壤中的微生物总活性更为困难。通过总结研究土壤微生物总活性常用的3种方法,在简略概括传统的土壤微生物呼吸测定法的基础上,详细介绍了放射性同位素标记法和RNA直接表征法的原理和操作流程,整理归纳了一些重要应用案例,比较分析了不同方法的优缺点,以期为选择研究土壤微生物总活性的适宜方法提供依据。
Total microbial activity （TMA） in soils is vital for understanding the roles of microorganisms in ecosystem processes. It can be defined as the sum of physiological activities of all the microbes at a given moment. As TMA is difficult to measure directly, a series of proxies, such as respiration rates, growth rates, and cellular RNA concentration, have been proposed. Here, methods used to measure soil TMA are synthesized and compared. （ 1 ） Respiration may be the process most closely related to life activities. Thus, respiration rates are the most commonly used proxies of soil TMA. The main limitation is that current methods to determine respiration rates usually cannot accurately reflect actual respiration rates. When respiration rates are measured using CO2 production or 02 consumption rates, they indicate carbon mineralization or aerobic respiration rates, respectively. （2） Microbes with higher growth rates are usually more active. Thus, growth rates are also widely used to indicate soil TMA. As biomacromolecule synthesis is approximately proportional to microbial growth rates, incorporation of radioactive isotope labeled precursors （i.e., thymidine, leucine, and acetate） can be employed to estimate microbe growth rates. Generally, trace radioactively labeled precursors are added to slurries （traditional methods） or extracted microbial suspensions （Baath＇s methods）. After a brief incubation, microbes are killed and the corresponding biomacromolecules are extracted to measure their radioactivity. Thymidine and leucine incorporation are commonly used to measure heterotrophic bacterial growth rates, while acetate incorporation is used to estimate growth rates of saprotrophic fungi. Radioactive isotope labeling methods are robust tools to estimate the growth rates of soil microbes. However, one critical problem is that TMA includes both growth activity and non-growth activity, whereas these methods only reflect the former. （3） Evidently, none of the methods based on respiration rates
出处
《生态学报》
CAS
CSCD
北大核心
2016年第8期2103-2112,共10页
Acta Ecologica Sinica
基金
国家自然科学基金项目(41230750)
中国科学院战略先导专项B课题(XDB05010200)
