Biomass Utilization by Gut Microbiomes

Bryan A White, Raphael Lamed, Edward A Bayer, Harry J Flint

Research output: Contribution to journalArticlepeer-review

126 Citations (Scopus)


Mammals rely entirely on symbiotic microorganisms within their digestive tract to gain energy from plant biomass that is resistant to mammalian digestive enzymes. Especially in herbivorous animals, specialized organs (the rumen, cecum, and colon) have evolved that allow highly efficient fermentation of ingested plant biomass by complex anaerobic microbial communities. We consider here the two most intensively studied, representative gut microbial communities involved in degradation of plant fiber: those of the rumen and the human large intestine. These communities are dominated by bacteria belonging to the Firmicutes and Bacteroidetes phyla. In Firmicutes, degradative capacity is largely restricted to the cell surface and involves elaborate cellulosome complexes in specialized cellulolytic species. By contrast, in the Bacteroidetes, utilization of soluble polysaccharides, encoded by gene clusters (PULs), entails outer membrane binding proteins, and degradation is largely periplasmic or intracellular. Biomass degradation involves complex interplay between these distinct groups of bacteria as well as (in the rumen) eukaryotic microorganisms. Expected final online publication date for the Annual Review of Microbiology Volume 68 is September 08, 2014. Please see for revised estimates.

Original languageEnglish
Pages (from-to)279-296
Number of pages18
JournalAnnual Review of Microbiology
Publication statusPublished - 16 Jun 2014

Bibliographical note

The authors appreciate financial support from the United States–Israel Binational Science Foundation (BSF), Jerusalem, Israel. Additional support was obtained through a grant (No. 24/11) issued to R.L. by The Sidney E. Frank Foundation through the Israel Science Foundation (ISF) and through a grant (No. 1349/13) to E.A.B. also from the ISF. E.A.B. is the incumbent of the Maynard I. and Elaine Wishner Chair of Bio-organic Chemistry. H.J.F. acknowledges support from the Scottish Government Food, Land and People Program. B.A.W. acknowledges support from the USDA grant #ILLU-538-333.


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