Biodegradable polymer Poly(3-hydroxybutyrate) is one of the promising alternatives for petroleum derived polymers. The present study focuses on a novel method for the synthesis of poly(3–hydroxybutyrate) (PHB) by two microorganisms, viz. Bacillus megaterium and Cupriavidus necator. Microbial cells were grown by utilizing fructose as a carbon source followed by fermentation using mineral salt medium. The breakage of cell wall was achieved by application of ultrasound wave and PHB powder was recovered using solvent extraction technique succeeded by drying at room temperature. The extracted PHB was characterized using FTIR, 1H and 13C NMR to observe the functional groups and moieties in the PHB molecule. The XRD characterization confirmed the partial crystalline nature of PHB. From the TGA analysis, the major step of weight loss of PHB derived by B. megaterium and C. necator in TGA analysis were found to be 415°C and 289°C respectively, which were comparatively higher than standard PHB (i.e. 260°C). Similarly, the maximum degradation temperature for standard PHB is 236°C, whereas the corresponding temperatures for PHB synthesized by B. megaterium and C. necator are 248°C and 277°C respectively. These results ascertain that the synthesized PHB has greater resistance to thermal degradation as compared to standard PHB. The melting point of synthesized PHBs were found to be 175–176°C, which is similar to standard PHB. The glass transition temperature of the synthesized PHBs varies from –8 to 6°C. The plausible reason behind the variances could be due to difference in crystallinity and molecular weight of polymer matrix. The 'degree of crystallinity' of synthesized PHBs are 44% and 23% respectively, which are lower than previously reported literatures. Thus, such PHBs extends its wide range of applications. Therefore, the synthesis of PHB via ultrasound-assisted route can significantly reduce the cost of fermentation process and simultaneously lessen the hazardous effect to environment and human health with a high potential of commercialization.

Production and characterization of biodegradable polymer poly (3-hydroxybutyrate) using ultrasound assisted extraction

256th National Meeting (2018)

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