Biosynthesis of polyhydroxyalkanoates employing a newly isolated Paramecium multimicronucleatum

Synthetic plastics are an environmental hazard due to their resistance to natural degradation leading to environmental pollution and perilous effects on ecosystem. Biodegradable plastics such as polyhydroxyalkanoates (PHAs) are the potential candidates to replace synthetic plastics. The present study focuses on the extraction and characterization of PHAs from an industrial-wastewater derived Paramecium multimicronucleatum. Paramecium culture was grown in the Bold Basal medium alone (hereafter used as positive control) and with the supplement of glucose (180 g/L) and cadmium chloride (10 g/L) to investigate the PHA production. The highest PHA production 0.28 g/L was achieved in 180 g/L glucose-supplemented medium and 0.12 g/L in positive control, while the lowest PHA production was 0.05 g/L in case of 10 g/L metal-treated samples. Fourier transform infrared spectroscopy (FTIR) and Gas chromatography–mass spectrometry-based (GC–MS) characterization showed the PHA to contain 3-hydroxybutyrate as the prime monomer (93.91%). The appearance of other esters such as pentadecanoic acid ethyl ester, hexadecanoic acid ethyl ester, and octadecanoic acid ethyl ester indicated the presence of medium-chain length PHAs. This is the first study reporting a ciliate, P.multimicronucleatum as a microbial cell factory producing substantial concentration of PHAs.