Degumming of Raw Silk Fabric with Help of Marine Extracellular Protease

Abstract

Protease secreting microbe was isolated and characterized on the basis of their morphological, biochemical, physiological and 16S rDNA based molecular properties. The extracellular protease was quantified and characterized. Protease was used for different time (4, 8, 12 and 24 h) at different temperature (RT and 37°C) for optimization of the degumming process for raw silk fabric with enzyme dosage (0.2-1 unit/cm² of fabric). Post-enzymatic treatment, the fabric quality and texture was compared with conventionally treated as well as untreated fabric in terms of degumming loss, tensile strength and yarn count and colour fastness to light/water. The isolate SM1 (Bacillus thuringensis) was able to grow in Carbon Minimal Salt Medium (CMSM) with jaggery or tamarind as the carbon source (0.3% w/v). Energy Dispersive X-Ray Fluorescense (EDXRF) data showed intracellular accumulation of heavy metal by the isolate. Extracellular protease was able to degum silk fabric within 4 h at RT with enzyme concentration of 0.8unit/cm² and the maximum degumming loss was 21.72%. Post enzymatic degumming, a shiny texture was observed under Environmental Scanning Electron Microscope (ESEM) and the yarn volume also increased. Utilization of CMSM made the process cost effective during large scale application. Intracellular metal accumulation and growth in a wide range of temperature and pH made the isolate a potential candidate for bioremediation. Extracellular protease with significant degumming property could be used as an eco friendly approach as compared to the conventional chemical treatment.