ABSTRACT
Little has been reported on the microbial degradation of silk. A few reports indicated that fungi and bacteria grew on silk. Fibroin, the main and at times the sole component of silk, is utilized worldwide for the production of artifacts of artistic interest. Some of the bacteria isolated from fibroin buried in soil or from enrichment cultures of silk cocoons were found capable of metabolizing fibroin in laboratory cultures and utilizing the protein as a sole source of carbon and nitrogen for growth, possibly by producing proteases that hydrolyze fibroin. Pulverized fibroin, to a final concentration of 2 mg/ml, was added to the medium devoid of all other carbon and nitrogen sources and inoculated with cells suspensions of pure cultures of each bacterial isolate. Naturally-aged silk fibroin analyzed in the work appears to possess a microbial flora essentially composed of bacteria. Differences were observed in the types of bacteria isolated from aged fibroin and from fibroin buried in soil.
