Bacterial Catalases

Abstract

All catalases, whether eukaryotic, prokaryotic, or archae, catalyze the same basic reaction, the dismutation of hydrogen peroxide to water and oxygen: 2H₂O₂ → 2H₂O + O₂. The enzyme presumably evolved to protect the cell by removing peroxide before cell damage was caused by peroxide radicals generated in chemical reactions. The degradation of H₂O₂ by various tissues was first studied in the early 1800s by Thénard, and the first report of a similar bacterial activity determined both in whole cells and in cell extracts appeared in 1893 (Gottstein 1893). The suggestion of a specific enzyme with the catalytic role of peroxide degradation (hence the name catalase) appeared in 1900 (Loew 1900), and this was confirmed with the purification of catalases from various sources, including beef liver (Sumner and Dounce 1937). The first report of a purified bacterial catalase from Micrococcus luteus appeared a decade later (Herbert and Pinsent 1948), but the simplicity of spotting a drop of H₂O₂ on the edge of a colony and watching for oxygen generation had much earlier made the presence or absence of catalase a diagnostic tool in bacterial taxonomy. Interest in bacterial catalases also derived from the potential role of the enzyme in pathogenesis wherein the infecting bacterium frequently has to survive a burst of active oxygen species, including H₂O₂ generated by the infected tissue.

There are a number of sources of H₂O₂ during the aerobic growth of any organism (Farr and Kogoma 1991). Reduction of oxygen as the terminal electron acceptor can give rise...