Halophilic Microorganisms as Potential Producers of Polyhydroxyalkanoates

Polyhydroxyalkanoates (PHA), a kind of storage energy produced by several microorganisms, have gained much attention over the years as a suitable alternate to non-biodegradable plastics. These are biodegradable, biocompatible, and non-toxic polymers, which are being used in various industrial and biomedical applications. PHA can also help to mitigate environmental pollution by replacing the non-biodegradable petroleum-derived plastics. However, the drawback for the use of PHA is its high cost of production at industrial scale. Halophilic microbes inhabiting diverse saline environment have unique physiology and adaptability that make them useful tools for exploring metabolites for industrial applications. PHA can be produced by halophilic microorganisms, which are less explored for their potential. PHA production by halophiles has certain advantages. As halophiles grow at higher salt concentrations, the growth of non-halophilic microorganisms can be prevented, thus eliminating the need for strict sterile operating conditions, and this reduces the cost of production of PHA. In addition, the polymer could be recovered by the hypo-osmotic shock of the cells enabling easy downstream processing. Reports are available on the various advances being made in the production of PHA in an economically feasible manner. These include optimization strategies focusing on halophilic microorganisms, such as supplying renewable carbon substrates, developing better bacterial strains, optimization of fermentation processes, engineering new pathways, etc. Thus, exploring new possibilities for improved PHA production in halophilic microorganisms, which are potential candidates for bioproduction in industrial setups, is the need of the hour. This chapter focuses on production of PHA and its optimization along with various applications of PHA.