Producers of Polyhydroxyalkanoates (PHA) are reported to stay at different ecological niches that are exposed naturally or accidentally to high organic matter or growth-limiting conditions like wastes from pulp and paper mills, wastes from dairy, wastes from agriculture, sites contaminated by hydrocarbons, treatment plants releasing activated sludges, rhizosphere, and effluents from industries. Extracellular secondary products such as rhamnolipids, polymeric substances as well as biohydrogen gas are also produced by a few among them. These microbes can produce valuable bioproducts like PHA with the simultaneous usage of waste materials having various origins as substrate and for this reason, these types of microbes are industrially important candidates in regard to production. An economical method could be the separation of the secondary products (intracellular and extracellular) by the implementation of an integrated system. Different microorganisms living under various environmental conditions that stimulate the microorganisms to store carbon as polyhydroxyalkanoates granules have been discussed in this review. We have also discussed various metabolites that are produced concurrently with PHA.
