Polyhydroxyalkanoates (PHAs) are a group of carbon and energy storage compounds that are accumulated during suboptimal growth by many bacteria, and intracellularly deposited in the form of inclusion bodies. Accumulation of PHAs is thought to be used by bacteria to increase survival and stress tolerance in changing environments, and in competitive settings where carbon and energy sources may be limited, such as those encountered in the soil and the rhizosphere. Understanding the role that PHAs play as internal storage polymers is of fundamental importance in microbial ecology, and holds great potential for the improvement of bacterial inoculants for plants and soils. This review summarizes the current knowledge on the ecological function of PHAs, and their strategic role as survival factors in microorganisms under varying environmental stress is emphasized. It also explores the phylogeny of the PHA cycle enzymes, PHA synthase, and PHA depolymerase, suggesting that PHA accumulation was earlier acquired and maintained during evolution, thus contributing to microbial survival in the environment.
Bibliographical noteFunding Information:
We thank Y. Davidov for discussions. This review was supported by “The Israel Science Foundation” founded by “The Academy of Sciences and Humanities,” and by the European Union-5th Framework contract QLK3-CT-2000-31759-ECO-SAFE. The work of S. Castro-Sowinski at The Hebrew University of Jerusalem was supported by Lady Davis Trust Fellowship.
- Bacterial Survival
- PHA Depolymerase
- PHA Metabolism
- PHA Synthase
- Poly-β-Hydroxybutyrate (PHB)
- Polyhydroxyalkanoates (PHA)