Intracellular storage: implications for microbial growth, element cycling and soil ecology

Description

Storage of resources like carbon and energy plays a central role in the lives of all organisms and alters their
ecological interactions. Some soil-derived bacteria can accumulate intracellular carbon in the form of polyhydroxybutyrate
(PHB) to as much as 50% of their dry biomass, while the accumulation of triacylglycerides (TAG) is
well known in eukaryotes like fungi. Soil is an extremely variable habitat, featuring seasonal and hydrological
fluctuations as well as intermittent and unpredictable inputs from roots, plant litter, and mesofauna. Storage is
especially important for growth and survival in variable environments like soil, yet has been largely neglected in
experimental and theoretical soil ecology.
This review briefly introduces the diversity of bacterial and fungal storage compounds, including PHB,
TAG, glycogen, trehalose, and polyphosphate. Principles of storage from general ecology are then reviewed,
to determine how these can apply to soil microbial communities. This shows that different modes of storage
are possible, affecting patterns of resource intake, reproduction and seasonal dynamics. An important general
conclusion is that storage profoundly affects survival and growth strategies in the context of variable and
unpredictable environments. It allows an organism to dynamically modulate its stoichiometry with respect to its
environment; and environmental variability and stoichiometry can, in turn, favor or disfavor storage. This has
implications for the interpretation of element flows and ecosystem stoichiometry. A systematic review of the
existing evidence from soil and the broader observational, experimental and theoretical microbiology literature
supports the relevance of these principles, and shows that storage compounds have fundamental consequences for
element cycles, experimental design, and how we conceptualize microbial life histories in soil.

Period	11 Apr 2019
Degree of Recognition	International