Streptococcus lyase is broad-spectrum and recombinant expression of Escherichia coli, can effectively kill a variety of streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus suis, Streptococcus mammary, Streptococcus agalactis, Streptococcus proteus and streptococcus equi. Streptococcus lyase is the only lyase which can kill Pathogenic bacteria of dental caries in the mouth.