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Absolute Abundance

Measuring absolute abundance, or the total microbial load, is vital for a thorough understanding of microbiome composition. While relative abundance highlights the distribution of different species within a sample, absolute abundance reveals the actual microbial count, offering a clearer perspective on community dynamics. Our Quantitative Microbiome Profiling (QMP) service provides accurate microbial quantification, enabling a deeper and more complete analysis of your microbiome data.

What is Absolute Abundance?

Understanding the total number of microbes present in a sample, known as absolute abundance or microbial load, is crucial for in-depth microbiome analysis. While relative abundance provides information on the proportion of different microbial species within a sample, absolute abundance reveals the actual quantity of microbes, offering deeper insights into microbial community dynamics.

For example, two samples might both contain 50% of bacterial species A and 50% of bacterial species B. However, if one sample has 2 million bacterial cells and the other has 20 million, their microbial loads are vastly different. Absolute abundance complements relative abundance data, enabling a more accurate interpretation of microbiome studies, particularly in contexts like human and animal health where microbial overgrowth or treatment efficacy is assessed.
 

Quantitative Microbiome Profiling (QMP)

We offer Quantitative Microbiome Profiling (QMP) services to determine absolute microbial abundance in your samples. QMP enhances the value of your microbiome data by integrating quantitative measurements, providing a complete picture of microbial community structure.

Methods for Quantifying Microbes

Several methods are available for quantifying microbes in a sample:

  • Spike-In Controls: Addition of known quantities of an external microbial species absent from the sample to calculate both relative and absolute abundances.

  • Quantitative PCR (qPCR): Amplification and quantification of target DNA sequences.

  • Flow Cytometry (Cell Counting): Direct counting of microbial cells.

We specialize in the two most efficient methods — spike-in controls and qPCR.

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Spike-In Controls

The spike-in method involves adding a known quantity of an external microbial species to your sample before DNA extraction. Since the spike-in species undergoes the same processing steps as the sample microbes, it accounts for any biases introduced during DNA extraction and sequencing. This method allows for precise calculation of both relative and absolute abundances.

Quantitative PCR (qPCR)

 

qPCR quantifies microbial DNA by amplifying specific DNA sequences. This method allows for calculation of both relative and absolute abundances without sacrificing sequencing reads. However, it can be affected by DNA extraction biases, as extraction efficiency may not be perfectly linear.

 

Compatibility with Analysis Methods

Our QMP services are fully compatible with both marker gene analysis (amplicon sequencing) and shotgun metagenomics. This flexibility ensures that you can integrate absolute abundance measurements into your preferred microbiome analysis workflow, enhancing the depth and reliability of your results.

  • Marker Gene Analysis (Amplicon Sequencing): Quantify specific microbial groups by targeting genes like 16S rRNA, ITS, or 18S rRNA.

  • Shotgun Metagenomics: Assess the entire microbial community by sequencing all genetic material present in the sample.

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Why Choose Our QMP Services

  • Accurate Microbial Load Assessment: Gain precise measurements of total microbial abundance in your samples.

  • Enhanced Data Interpretation: Integrate absolute abundance data with relative abundance for a more complete microbiome analysis. 

 

 

  • Expert Guidance: Our experienced team provides personalized support to determine the best quantification method for your study.

  • Optimized Protocols: Benefit from validated protocols that minimize biases and maximize data quality.
 

References

Vandeputte, D., Kathagen, G., D’hoe, K. et al. Quantitative microbiome profiling links gut community variation to microbial load. Nature 551, 507–511 (2017). https://doi.org/10.1038/nature24460

Morton, J.T., Marotz, C., Washburne, A. et al. Establishing microbial composition measurement standards with reference frames. Nature Communications 10, 2719 (2019). https://doi.org/10.1038/s41467-019-10656-5