Response by the Authors:
We thank Dr. Mestrovic for his constructive comments and we acknowledge that we made that statement that there are approximately 1014 microbes associated with the human gut based on the commonly held perspective found in the literature. We also acknowledge that precision in language is essential to the scientific discussion and that hyperbole should be avoided. The statement made in our review article – where we discussed the influence of resident microorganisms on the host - was meant to emphasize the enormous size of the microbiota. The recent paper published by Sender and colleagues(1) does make a good case that the relative proportion of microbes to host cells may not be in agreement with the general believe about the 10:1 ratio and that it may rather be 1:1 or 3:1. These numbers and ratios deserve additional detailed analysis in individuals where the composition of microbial or host cells is furthermore altered due to antibiotics, radiation, chemotherapy or the disease itself. As newer and more sophisticated techniques become available, it is likely that the science of host-microbe interactions will move away from quantitative (I.e., abundance) comparisons to more relevant metabolic and niche analyses.
Acknowledgments
Conflicts of Interest and Source of Funding:
Supported by R56 AI116715, R01 HL56067, R01 AI112613, and R01 AI 34495.
Footnotes
The authors have no conflict of interest to disclose.
Reference:
- 1.Sender R, Fuchs S, Milo R. Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans. Cell 2016;164(3):337–40. doi: 10.1016/j.cell.2016.01.013.PubMed PMID: 26824647. [DOI] [PubMed] [Google Scholar]