Ipplication of Alkaline Serine Protease for Silk Fibers Processingin Textile Industry

摘要

Degumming, a process of removal of sericin from the crude silk fiber, contributes to the shine, softness and the elegant drape of silk. In the present study, degumming of silk from the silk cocoon (Bombyx mori) obtained from white mulberry tree (Momsalba) was successfully done using an alkaline serine protease from a hyper-producing strain of Bacillus licheniformis SBP-114. A crude enzyme preparation at 10% concentration achieves the commercially desired silk degumming levels (28.5%) in 4 h at 40°Cand pH 9.0. Scanning Electron Microscopic (SEM) studies revealed that the removal of serecin from the silken threads makes them loose and crisp, full and shiny. Knowing the commercial importance of this enzyme in the textile industry, production of theprotease was scaled up in a 200 L fermentor using an optimized medium containing wheat bran and soybean meal, which resulted in 4586 U/ml of protease production within 22 h, with a productivity of 208.45 U/ml/h. This cost effective enzyme production, itsscalability up to 200 L fennentor size and amenability of unprocessed crude culture broth for the silk degumming process makes this alkaline serine protease a viable alternative to the conventional procedure, and gives a new benchmark for the fiber andtextile industry.