An Alcohol Oxidation System in Streptococci Which Functions without Hydrogen Peroxide Accumulation.

Previous reports on the enzymic activities of lactic acid bacteria have shown the presence of alcohol dehydrogenases in several strains of streptococci (Gunsalus and Wood, 1942). The presence of this enzyme system in orgams generally characterized by a pure lactic acid fermentation is perhaps somewhat unexpected, and may indicate a wider distribution of alcohol enzymes than is generally realized. Alcohol oxidation systems have been reported for several types of cellsAcetobacter, Escherichia coli, yeast, liver, etc.-which contain rather complete respiration systems. Some cells are able to use energy released during this oxidation (Wieland and Pistor, 1936; Barker, 1941). As streptococci lack the usual iron-containing oxidation catalysts, their respiration is frequently considered to be "unphysiological" and perhaps of little, if any, value to the organisms. The accumulation of hydrogen peroxide in many cases (Bertho and Gluck, 1932; Sevag, 1933) is cited as evidence of the injurious nature of the oxidation. More recently, however, Lipmann (1939) has shown that the pyruvic acid oxidation system of Lactobacillus delbrueckii liberates energy which is available to the cells in the form of energy-rich phosphate. Gunsalus and Sherman (1943) have found that several lactic organisms require oxygen in order to utilize glycerol as an energy source. Further study indicates that glycerol oxidation is accompanied by a disappearance of inorganic phosphate (Gunsalus and Umbreit, 1942). With this evidence of the value of oxidation to lactic acid organisms, the alcohol oxidatiorr system has been studied in some detail. The present report includes a study of the properties of the alcohol oxidation system with intact cells of a hemolytic lactic acid organism, Streptococcus mastitidis. The products of oxidation have been determined. The oxidation has been found to proceed rapidly, but, in contrast to most oxidations by lactic bacteria, hydrogen peroxide does not accumulate.