Abstract:
Polyhydroxyalkanoates (PHAs) are microbially synthesized polymers that serve as a sustainable alternative to conventional plastics. However, their large-scale production faces challenges due to high production costs. Conventionally, most microorganisms have been reported to produce only PHAs when cultivated under conditions of high carbon content and limited nitrogen and phosphate. In contrast, this study explores the simultaneous production of PHAs and high-value carotenoids by employing halophilic archaea. A pigmented halophilic archaeon Haloarcula argentinensis GUAg231, isolated from the multipond solar saltern of Goa, India, has been studied to co-produce PHAs and carotenoids with 1 percent glucose as the carbon source. The process resulted in a PHA yield of 2.96 plus-minus 0.12 g/L and a carotenoid yield of 3.75 plus-minus 0.03 mg/L. Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) analysis confirmed the PHA produced as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P(3HB-co-3HV) with a 13.98 percent hydroxyvalerate (HV) fraction, while the major carotenoid in the halophilic archaeon was identified as bacterioruberin. This dual-production strategy could enhance the economic feasibility of PHA manufacturing, highlighting the potential of halophilic archaea as a viable approach with opportunities for optimization to achieve higher yields of PHA and carotenoids.
