Comparison of poly(butylene succinate) biodegradation by Fusarium solani cutinase and Candida antarctica lipase

Poly(butylene succinate) (PBS) was hydrolyzed by two different enzymes: cutinase from Fusarium sp. and lipase from Candida antarctica (Lipozyme CALB). The differences between the PBS residues degraded over time were investigated with respect to their morphology, crystallinity and chemical structures. The degradation mechanism of PBS films using the two enzymes was further investigated by establishing a model. The results show that the PBS weight loss when degraded by cutinase was higher than when degraded by Lipozyme CALB under the same conditions. The PBS degradation mechanisms by cutinase and Lipozyme CALB occur by surface erosion and bulk erosion, respectively. Scanning electron microscopy shows that the diameter of pits formed after degradation by cutinase was approximately 3 times larger than those formed by Lipozyme CALB. The change in crystallinity is related to the type of enzyme used during the degradation process. Following Lipozyme CALB degradation, the degree of PBS crystallinity decreased with increasing time, leading to increased weight loss of the PBS films. Conversely, the PBS crystallinity was nearly unchanged following cutinase degradation. Powder X-ray diffraction indicates that the crystalline structure does not change during enzymatic hydrolysis. Fourier transform infrared spectroscopy confirms that the resulting structure of the degraded PBS is similar when treated with cutinase and Lipozyme CALB. Mass-spectrometric analysis suggested an endo-type action mode for both the enzymes.