Characterization of a cutinase from Myceliophthora thermophila and its application in polyester hydrolysis and deinking process

A gene encoding cutinase (MtCUT) from Myceliophthora thermophila was expressed in Pichia pastoris. The optimal temperature and pH for MtCUT were 30 degrees C and 8.5, respectively. MtCUT showed high activities toward a broad range of p-nitrophenyl esters, and the highest specific activity was recorded for p-nitrophenyl butyrate. MtCUT hydrolyzed and broke down apple cutin into C16 and C18 family fatty acids. MtCUT could efficiently degrade polycaprolactone (PCL), the weight loss of which was 78.5% in 36 h. In addition, MtCUT could degrade PVAc, a kind of adhesive that is frequently used in papermaking and in synthetic toner or ink. Its performance in the deinking of waste papers was investigated and compared with that of commercial lipase in this study. The results showed that an ink removal efficiency of 78.4% on laser-printed paper and 81.3% on newspaper was obtained using MtCUT at 30 degrees C, which was better than that of lipase from Candida rugosa (CrLIP) (77.0% and 76.0%, respectively). The properties of the MtCUT-treated samples were similar to that of the control samples. This revealed that the cutinase MtCUT from M. thermophila has a great potential in PCL hydrolysis and the deinking process.