A λ phage DNA library of Serratia marcescens was constructed and a clone carrying the gene coding for chitobiase (E.C.220.127.116.11) was isolated and characterized. Deletion analysis limited the cloned region to 4.5 kb that is capable of efficient expression of chitobiase. Escherichia coli cells harboring a plasmid carrying the cloned gene express chitobiase constitutively. The molecular weight of the protein is about 95000 daltons. In exponentially growing E. coli cells the chitobiase enzyme was found to be secreted into the periplasm.
- Serratia marcescens