Molecular Cloning ofClostridium perfringensEpsilon-Toxin Gene and Its High Level Expression inE. coli

Abstract

A gene coding for epsilon-toxin was isolated from a field isolate ofClostridium perfringenstype D by PCR amplification and was cloned under the control of T5 promoter fused with six-histidine tag at the amino terminal end.Escherichia colicells harbouring this construct expressed high levels of the recombinant protein in the form of inclusion bodies. The protein was purified using single step affinity chromatography on a Ni2+-nitrilotriacetic acid (NTA) agarose column. Upon immunization of rabbit with the purified recombinant protein, high antibody titre was detected. The antibodies raised against the recombinant protein were able to recognize the recombinant as well as the native toxin. Anti epsilon-toxin monoclonal antibody was able to detect the recombinant protein in a Western blot. N-terminal sequence of the recombinant protein matched with the known sequence of the toxin. At the shake flask level, up to 20 mg of pure epsilon-prototoxin was produced per litre of culture.