Comparison of quantification methods and subsequent characterization of polyhydroxybutyrate film sample utilizing pretreated cane molasses as carbon source

Abstract

Polyhydroxybutyrate (PHB) is a biodegradable polyester synthesized as intracellular carbon and energy storage for numerous bacteria and archaea. PHB has been used extensively in biomedical industry. The gas chromatography (GC) method for PHB quantification has some drawbacks, such as large sample size required and involves tedious sample preparation. In this study, reactive pyrolysis-gas chromatography (reactive Py-GC) was applied to determine the PHB content in bacterial biomass. Bacillus sp. was cultured in mineral salts medium containing various concentrations of pretreated molasses (10 – 30 g/L) as a sole carbon source. The PHB content obtained by both methods; GC and reactive Py-GC were compared. The obtained PHB was cast into film and the physical properties was determined by DSC and TGA. The biodegradability of PHB film sample was performed by soil burial biodegradation test. Based on the peak intensities of reactive Py-GC analysis, the PHB contents were determined precisely and rapidly without any cumbersome sample pretreatment. Furthermore, the values of the PHB contents coincided overall with those obtained by the conventional GC method with correlation coefficient (R2) 0.9766. The melting temperature and degree of crystallinity were 172 °C and 61 %, respectively. The PHB film sample used in this study can biodegrade completely within 12 days.