Linking ecology with economy: Insights into polyhydroxyalkanoate-producing microorganisms

Polyhydroxyalkanoates (PHA) constitute a group of microbial biopolyesters with important ecosystem functions and a high biotechnological potential. During the past decade, the rapid development of new molecular and microscopic techniques resulted in novel insights into the ecology of PHA-producing bacteria in aquatic and terrestrial microenvironments. Ecosystems showing fluctuating availability of carbon or transient limitation of essential nutrients, e. g. the rhizosphere of plants or estuarine sediments, contain a broad number of various PHA producers. PHA-producing microorganisms show a widespread phylogenetic diversity and are often characterized by a symbiotic or syntrophic life style. PHA are already produced commercially in large-scale fermentation. However, they have to compete economically with petrol-based polymers. Hence, the development of low-cost production strategies on the basis of diverse renewable materials is a crucial challenge. Ecological knowledge is required for these developments, which links both parts of the review together. The article highlights how a better understanding of the ecology of PHA-producing microorganisms can lead to a broader application of microbial biopolymers on the basis of sustainable production processes. These processes have to be evaluated by means of life cycle assessment and Cleaner Production studies prior to their industrial implementation.