Bacteroidetes bacteria in the soil: Glycan acquisition, enzyme secretion, and gliding motility
Book chapter, 2020

The secretion of extracellular enzymes by soil microbes is rate-limiting in the recycling of biomass. Fungi and bacteria compete and collaborate for nutrients in the soil, with wide ranging ecological impacts. Within soil microbiota, the Bacteroidetes tend to be a dominant phylum, just like in human and animal intestines. The Bacteroidetes thrive because of their ability to secrete diverse arrays of carbohydrate-active enzymes (CAZymes) that target the highly varied glycans in the soil. Bacteroidetes use an energy-saving system of genomic organization, whereby most of their CAZymes are grouped into Polysaccharide Utilization Loci (PULs). These loci enable high level production of specific CAZymes only when their substrate glycans are abundant in the local environment. This gives the Bacteroidetes a clear advantage over other species in the competitive soil environment, further enhanced by the phylum-specific Type IX Secretion System (T9SS). The T9SS is highly effective at secreting CAZymes and/or tethering them to the cell surface, and is tightly coupled to the ability to rapidly glide over solid surfaces, a connection that promotes an active hunt for nutrition. Although the soil Bacteroidetes are less well studied than human gut symbionts, research is uncovering important biochemical and physiological phenomena. In this review, we summarize the state of the art on research into the CAZymes secreted by soil Bacteroidetes in the contexts of microbial soil ecology and the discovery of novel CAZymes for use in industrial biotechnology. We hope that this review will stimulate further investigations into the somewhat neglected enzymology of non-gut Bacteroidetes.


Soil bacteria

Type IX secretion system

Carbohydrate-active enzymes

Polysaccharide utilization loci



Johan Larsbrink

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Wallenberg Wood Science Center (WWSC)

Lauren S McKee

Royal Institute of Technology (KTH)

Wallenberg Wood Science Center (WWSC)

Advances in Applied Microbiology

978-012820703-1 (ISBN)

Driving Forces

Sustainable development

Subject Categories

Soil Science

Biochemistry and Molecular Biology

Environmental Sciences related to Agriculture and Land-use




Basic sciences

Areas of Advance

Life Science Engineering (2010-2018)





More information

Latest update

5/7/2021 1