Global distribution of microbial abundance and biomass in subseafloor sediment
Jens Kallmeyera,b,1,2, Robert Pockalnyc,1, Rishi Ram Adhikaria, David C. Smithc, and Steven D’Hondtc
Author Affiliations
aInstitut für Erd- und Umweltwissenschaften, Universität Potsdam, 14476 Potsdam, Germany;
bHelmholtz Centre Potsdam, GFZ German Research Centre For Geosciences, Section 4.5 Geomicrobiology, Telegrafenberg, 14473 Potsdam, Germany; and
cGraduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882
Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved July 16, 2012 (received for review March 5, 2012)
Abstract
The global geographic distribution of subseafloor sedimentary microbes and the cause(s) of that distribution are largely unexplored. Here, we show that total microbial cell abundance in subseafloor sediment varies between sites by ca. five orders of magnitude. This variation is strongly correlated with mean sedimentation rate and distance from land. Based on these correlations, we estimate global subseafloor sedimentary microbial abundance to be 2.9⋅1029 cells [corresponding to 4.1 petagram (Pg) C and ∼0.6% of Earth’s total living biomass]. This estimate of subseafloor sedimentary microbial abundance is roughly equal to previous estimates of total microbial abundance in seawater and total microbial abundance in soil. It is much lower than previous estimates of subseafloor sedimentary microbial abundance. In consequence, we estimate Earth’s total number of microbes and total living biomass to be, respectively, 50–78% and 10–45% lower than previous estimates.
deep biosphere cell enumeration global microbial biomass subsurface life
Footnotes
↵1J.K. and R.P. contributed equally to this work.
↵2To whom correspondence should be addressed. E-mail: kallm@gfz-potsdam.de.
Author contributions: J.K., R.P., and S.D. designed research; J.K., R.P., R.R.A., and D.C.S. performed research; J.K., R.P., and S.D. analyzed data; and J.K., R.P., and S.D. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1203849109/-/DCSupplemental.
Freely available online through the PNAS open access option.
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