Purification and Gene Cloning of Catalase from Staphylococcus warneri ISK-1

To investigate the possibility of applying staphylococcal catalase to eliminate H₂O₂ in lactic acid fermentation, an intracellular catalase from Staphylococcus warnen ISK-1 which exhibited high catalase activity was purified to homogeneity in a six-step purification procedure. The subunit molecular mass of the purified enzyme determined under denaturing conditions was 64,000. The absorption spectrum of the catalase showed a soret band at 406 nm, indicating that the enzyme is a heme protein. K_m and V_max of the catalase for H₂O₂ were 59 mM and 42,700 U/mg, respectively. The catalase showed a broad optimum pH (5.5-9.5) and stability to organic solvents. We cloned a catalase gene from S. warneri ISK-1 genome. Nucleotide sequence analysis of a 2.2-kb DNA fragment revealed an open reading frame of 1515 bp, called katA, encoding a protein of 504 amino acid residues. The predicted amino acid sequence showed a high homology with other typical catalases. No similarities to bacterial catalase-peroxidase type enzymes were found.