CHARACTERIZATION OF SUPEROXIDE-DISMUTASE GENES FROM GRAM-POSITIVE BACTERIA BY POLYMERASE CHAIN-REACTION USING DEGENERATE PRIMERS

An internal fragment representing approximately 85% of sod genes from seven Gram-positive bacteria was amplified by using degenerate primers in a polymerase chain reaction assay. The DNA sequences of sod polyme rase chain reaction products from Clostridium perfringens, Enterococcu s faecalis, Enterococcus faecium, Lactococcus lactis, Staphylococcus a ureus, Streptococcus agalactiae, Streptococcus pneumoniae, and Strepto coccus pyogenes were determined. Comparisons of their deduced amino ac id sequences with those of the corresponding regions of the SOD protei ns from Bacillus stearothermophilus, Listeria monocytogenes, and Strep tococcus mutans revealed strong relatedness. Phylogenetic analysis of SOD peptides showed that members of the genera Streptococcus and those of the genera Enterococcus constitute two well-supported monophyletic groups. The method described in this study provides a means for easy recovery of sod genes and the construction of sod mutants of various G ram-positive pathogens.