NEW RESEARCH RESULTS: Novel polyesterase to hydrolyse cutin and suberin

Tuesday, 03 February 2009 19:03

Cutin and suberin are lipid-derived insoluble polyesters that serve as structural components of the outer barriers of plants. Significant amounts of cutin are present in different agricultural and food raw materials such as cereals, berries, fruits and vegetables and their processing by-products, whereas the bark of cork oak and birch are rich in suberin. These polymers are estimated to be the third most abundant natural polymers after cellulose and lignin.

Cutin can be depolymerized by chemical cleavage of the ester bonds. However, epoxy, hydroxy and carboxylic acid functionalities are not always retained when harsh chemical treatments are applied. Thus enzymatic depolymerization of cutin is an attractive option and could result in formation of both monomers and oligomers with unmodified functionalities.

In the work of Hanna Kontkanen et al. novel cutinolytic polyesterases that could be exploited in treating agricultural, food and forest raw materials, as well as their processing by-products, were identified. Cutinase-like genes from the basiodiomycete Coprinopsis cinereus were cloned and expressed in Trichoderma reesei. One of the expressed cutinases, CcCUT1, was purified by immobilized metal affinity chromatography. CcCUT1 had higher activity on shorter (C2-C10) fatty acid esters of p-nitrophenol than on longer ones and it also exhibited lipase activity. It had optimal activity between pH 7 and 8 but retained activity over a wide pH range. The enzyme retained 80 % of its activity after 20 h incubation at 50 °C, but residual activity decreased sharply at 60 °C. The enzyme was able to depolymerize apple cutin and birch outer bark suberin.

All in all, cutinases could have potential in a wide variety of applications including both food and non-food areas. Cutinases could be used in processing of berries or in valorisation of different plant by-products to food ingredients. Furthermore cutinases have potential in e.g. laundry and dishwashing applications to remove fats, as well as in cotton bio-scouring and surface modification of synthetic polyester fibres.


Reference:

Kontkanen, H., Westerholm-Parvinen, A., Saloheimo, M., Bailey M., Rättö, M., Mattila I., Mohsina, M., Kalkkinen, N., Nakari-Setälä, T., Buchert, J. A novel polyesterase from Coprinopsis cinereus hydrolysing cutin and suberin. Appl. Environ. Microb. (2009), In Press.

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