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

An alkaline (optimum pH 10.0) and thermo stable (optimum temperature 60 degreesC) 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 mu mol/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. (C) 2001 Elsevier Science Ltd. All rights reserved.