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SUMMARY: The chains which are formed when rod-shaped Gram-positive bacteria are grown in media containing low concentrations of magnesium, undergo fission when exposed to the action of lysozyme. This effect is not produced by various other hydrolytic enzymes including the carbohydrases, cellulase and hyaluronidase. Fragmentation of the filamentous forms of the Gram-positive organisms, however, is not produced by lysozyme. A crude preparation obtained from mechanically disintegrated Clostridium welchii cells resembled lysozyme in its action on the magnesium-deficient organisms. The growth of Gram-positive rod-shaped bacteria in complex media (peptone water or amino-acid mixtures) deficient in magnesium, results in the inhibition of cell division and in the formation of filamentous cells (Webb, 1948a, 1949, 1951). Since magnesium deficiency does not affect the division of the nuclear structures (chromatinic bodies) and, with increasing concentrations of mag- nesium, the morphology of the cells changes from filaments to chains and thence to isolated normal rods (Webb, 1949), it appears probable that magnesium is involved in one of the final stages of cell division. From these considerations it was of interest to determine whether, by the action of hydrolytic enzymes of known specificity, it was possible to cause fragmentation of the filaments or the chains. Since little was known of the chemical nature of the cellular components affected by magnesium deficiency, a study was made of the action of various groups of enzymes, each of which exhibited hydrolytic activity against particular macromolecular constituents of the cells. MATERIALS AND METHODS Source of enzymes The enzymes used in the following experiments are summarized below. The pH value at which the action of a given enzyme was studied and its concentration (mg./5 ml.) in a mixture of 0.85 yo (w/v) sodium chloride (4-0 ml.) and 0.2 M acetate, phosphate or veronal buffer (1.0 ml.) are given in parentheses. Ribonuclease (pH 7.0,O.l mg.) was isolated from beef pancreas by the method of Kunitz (1940). It was free from phosphatase, nucleotidase, lipase, proteinase, adenine and guanine deaminase and deoxyribonuclease activities. Deoxyribonuclease (pH 7-0,O.l mg. and 0.1 mg. MgSO, .7H,O to activate) was obtained from beef pancreas by McCarty's (1946) method, and purified as described by Overend & Webb (1950). The preparation, dried from the frozen

journal of general microbiology/journal of general microbiology

The Influence of Magnesium on Cell Division 6. The Action of Certain Hydrolytic Enzymes on the Filamentous and Chain Forms of Gram-Positive Rod-Shaped Organisms