Application of an alkaline and thermostable polygalacturonase from Bacillus sp. MG-cp-2 in degumming of ramie ( Boehmeria nivea) and sunn hemp ( Crotalaria juncea) bast fibres

Abstract

An alkaline (optimum pH 10.0) and thermo stable (optimum temperature 60°C) polygalacturonase from Bacillus sp. MG-cp-2 has been applied for the degumming of ramie ( Boehmeria nivea) and sunn hemp ( Crotalaria juncea) bast fibres in comparison to the conventional chemical degumming process. Sunn is an East Indian plant with a valuable fibre resembling hemp and lighter and stronger than jute. Of the three treatments i.e. enzymic, chemical, and ‘chemical+enzyme’, the third treatment was most promising for degumming. The maximum reducing sugar released from the ramie and sunn hemp fibre were 9.4 and 7.6 μmol/ml, respectively, whereas the percent reduction in the fibre weight of ramie and sunn hemp fibre were 37 and 56%, respectively, after 11 h of treatment with chemical and enzyme. The scanning electron microscopic studies also revealed a complete removal of non-cellulosic gummy material from the surface of ramie and sunn hemp fibres. On the basis of this study, it is recommended that a mild chemical treatment of plant fibre is necessary before its enzymic treatment, since neither chemical nor enzymic treatment is sufficient.