Enzyme II, the membrane-bound component of the system, determines its carbohydrate specificity; five such enzymes have thus far been identified.A close relationship between the phosphotransferase and carbohydrate permease systems was reported earlier4 based on results obtained with osmotically shocked Escherichia coli W2244;5 the cells lost most of their HPr along with their ability to transport two glycosides. Other transport systems were subsequently studied by this method.6-8In the course of the present experiments, results obtained9' 10 with mutants of E. coli and Aerobacter aerogenes (lacking either enzyme I or HPr) showed that the phosphotransferase system was involved in either the transport and/or metabolism of five sugars. The present report is concerned with a single mutation in Salmonella typhimurium that results in an inability to grow on nine carbohydrates concomitant with a loss of enzyme I. The-mutant was also seriously defective in its ability to transport sugars into the cell. We therefore conclude that the phosphotransferase system is intimately involved in sugar transport.Materials and Methods.-Unless otherwise specified, all materials were obtained from commercial sources. The parent strain, Salmonella typhimurium SB497 (rfb-816, his-1367), was grown in liquid culture in a mineral-salts medium, as described in Table 1, or in nutrient broth (Difco). To obtain the desired mutant, the parent strain was treated with nitrosoguanidine,"1 grown in the mineral medium in the presence of melibiose and penicillin,'2 and the resulting culture spread on eosin-methylene blue plates (EMB) containing melibiose in order to obtain melibiose-negative colonies. Several such colonies were only melibiose-negative, while one mutant, designated SB703, lacked the ability to ferment eight other carbohydrates, as described below. This carbohydrate lesion was termed car-, by analogy with the car-mutants of Staphylococcus aureus.'3 Fermentation tests were conducted on peptone EMB plates,'4 or on the more sensitive bromthymol blue indicator plates,'6 in the presence of 1 per cent carbohydrate.

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