• myGriffith
    • Staff portal
    • Contact Us⌄
      • Future student enquiries 1800 677 728
      • Current student enquiries 1800 154 055
      • International enquiries +61 7 3735 6425
      • General enquiries 07 3735 7111
      • Online enquiries
      • Staff phonebook
    View Item 
    •   Home
    • Griffith Research Online
    • Journal articles
    • View Item
    • Home
    • Griffith Research Online
    • Journal articles
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

  • All of Griffith Research Online
    • Communities & Collections
    • Authors
    • By Issue Date
    • Titles
  • This Collection
    • Authors
    • By Issue Date
    • Titles
  • Statistics

  • Most Popular Items
  • Statistics by Country
  • Most Popular Authors
  • Support

  • Contact us
  • FAQs
  • Admin login

  • Login
  • A reviewon the methods for measuring total microbial activity in soils

    Author(s)
    Che, RX
    Wang, F
    Wang, YF
    Deng, YC
    Zhang, J
    Ma, S
    Cui, XY
    Griffith University Author(s)
    Che, Rongxiao
    Wang, Fang
    Year published
    2016
    Metadata
    Show full item record
    Abstract
    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 ...
    View more >
    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 O2 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 (Bååth'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 or incorporation of radioactive isotope labeled precursors can accurately link microbial activity with their identities. However, this issue can be resolved through using methods based on RNA. RNA correlates closely with protein synthesis, which is involved in most metabolic processes. Therefore, RNA concentration is assumed an ideal indicator of microbial activity. Generally, mRNA can be used to indicate the activity of specific metabolic processes, including nitrogen fixation and denitrification, whereas rRNA is a proxy of soil TMA. As cellular concentrations of small subunit rRNA (SSU rRNA) are proportional to total cellular rRNA concentrations, SSU rRNA copies can serve as an indicator of soil TMA and the ratio of SSU rRNA copies to SSU rRNA gene copies can be used to determine average microbial activity in soil. Additionally, active microbial community structure can be illustrated using profiling methods, such as clone library, T-RFLP, and high-throughput sequencing, based on SSU rRNA. These approaches can simultaneously identify soil microbes and their activity via in situ measurements. However, there is still no adequate evidence to support the assertion that the methods based on SSU rRNA can accurately reflect microbial activity, especially for non-growth activity. In conclusion, none of these methods are perfect to determine soil TMA; and a combination of suitable methods should be selected for individual ecosystems.
    View less >
    Journal Title
    Shengtai Xuebao/ Acta Ecologica Sinica
    Volume
    36
    Issue
    8
    DOI
    https://doi.org/10.5846/stxb201410262093
    Subject
    Ecological applications not elsewhere classified
    Ecology
    Soil sciences
    Publication URI
    http://hdl.handle.net/10072/142618
    Collection
    • Journal articles

    Footer

    Disclaimer

    • Privacy policy
    • Copyright matters
    • CRICOS Provider - 00233E

    Tagline

    • Gold Coast
    • Logan
    • Brisbane - Queensland, Australia
    First Peoples of Australia
    • Aboriginal
    • Torres Strait Islander