Underappreciated microbes now get credit for holding down two jobs in soil
(PHYSorg.com Biology)

In soil, bacteria and other microbes are well known for their ability to decompose organic materials, releasing carbon to the atmosphere. Less understood is how microbes add persistent carbon compounds to the soil. Scientists reviewed both roles via the concept of a `microbial carbon pump.` The pump is proposed as a mechanism for integrating how the contrasting breakdown and synthesis activities of microbes-coupled with the `entombment` of microbial residues-influence carbon levels in the soil.