Isolation, Identification, And Characterization Of Fibroin-Degrading Microorganisms

With the developement of the multi-utilization of silk, the use of the degradation products of fibroin become more and more. At present, in order to produce the peptide of silk, the salt, acid or alkali are used to degradate the silk. But peptide chain produced by salt degradation is too long to use, while using acide or alkali to degradate the silk, the amino acid will be destroyed. What's more, the subsequent processes of these methods such as doffing salt or acide are very complex. So the best method of producing silk polypeptide is to degradate silk by enzyme. However, as a typicalβ-keratin, the fibroin is hard to be degradated by ordinary proteinase. At present, the proteinases which can degradate the silk have been separated from silkworm moth andmicroorganism. But the origin and stability limit their use. Hence, we isolated 7 strains that can utilize the fibroin as the only carbon and nitrogen resources. Their capability of degradating fibroin, wood and feather is studied. And one strain that is the most efficient to degradate fibroin was classified. The base for further study of microbial silk proteinase was established. The mostly results are as follows:1. The soil is the topsoil of oak hurst in the Mount Tai and the lawn in Shandong Agricultural University. Before isolating, the condition that suitable to the microbial growth was created in order to increase the amount of intent microorganism . The microorganism was separated by spread plate method and streak plate method. At last, seven strains, which can utilize fibroin as the only carbon and nitrogren resources, are obtained.2. The seven strains were filtrated according to the capability of degradating silk pieces in different substrate, temperature and the silk pieces which is in natural conditions. The strains numbered C1, C2 and C3 are all able to degradate the nature silk, but the C3 has the biggest capability of degradating fibroin. It can rupture the silk piece within 14 days,and it is more efficient than the microoganism isolated by an Italian scholar.3. The results of examination of degradating other keratin indicated that these strains could degradate the feather, whether it was braised in 121℃or not. But the feather without braising was degradated a little slower. These...