Abstract
A green, efficient, and economic method to recover polydroxybutyrate (PHB) from Burkholdria cepacia culture broth by pancreatin was systemically studied and characterized. Transmission electron microscopy (TEM) indicated efficient cell lysis and PHB granules release by pancreatin. Pretreatment
methods including heat shock, surfactant digestion, and oxidizing agent digestion were compared. Thermal pretreatment prior to enzymatic digestion was found effective and no chemicals were needed. Pancreatin showed a relatively higher activity in the temperature range between 50 °C and
70 °C. Basic pH environment renders higher pancreatin digestion. The extent of cell lysis was found increasing linearly with the enzyme to biomass ratio in the range between 0.01 and 0.03. Through the approach thermal treatment-pancreatin digestion following heat pretreatment, the
purity of PHB increased from 43.2% to 90.6%, and recovery of PHB reached 93.5%. Structural composition characterization by NMR indicated that PHB recovered by pancreatin is comparable to solvent-extracted PHB. Successful protein removal was achieved. Polymer degradation was considered negligible
as molecular weight reduction was small. Thermal properties of PHB were characterized by DSC and TGA. Compared with solvent extracted polymer, PHB recovered by pancreatin exhibited a similar glass transition temperature, melting temperature, and decomposition temperature, but higher crystallization
temperature.