Observations on a strain of Neisseria meningitidis in the presence of glucose and maltose.

This report concerns the differential utilization of the disaccharide maltose and of its constituent monosaccharide glucose by a strain of Neisseria meningitidis. In the presence of maltose the organism produced changes which in the presence of glucose either were not detected or appeared at a greatly reduced rate. For example, it was noted that inorganic phosphate disappeared only with maltose and the decrease of reducing substances, and the production of acid occurred to a greater extent in the presence of maltose than it did with glucose. Similar observations were madewith growing cultures, with washed-cell suspensions in which the organism was in the so-called "resting state," and with "cell-free" extracts. Growth studies are emphasized here. Work on the other two test systems will be recorded subsequently. According to Fischer's theory (1898) of the indirect utilization of a compound sugar, microorganisms hydrolyze the oligosaccharide into its constituent simple sugars before the process of fermentation can take place. On the other hand, Willstiitter and Rohdewald (1937) showed that a yeast converted maltose completely into a polyose, which then was fermented. These findings were interpreted to indicate a direct utilization of the complex sugar without its preliminary hydrolysis. Recent reports published from Doudoroff's (1949) and Monod's (1950) laboratories suggest a resolution of these theories by their description of the action of various "transglucosidases." The preferential utilization of oligosaccharides by bacteria is considered to depend upon adaptive processes in the sense of Karstr6m (1938). Our observations indicate that a strain of Neisseria meningitidis utilizes maltose more rapidly than glucose as a result of a training process "due to the selection of variants which occur under normal conditions in the parent culture" (Dubos, 1945). This selective process was found to depend upon the concentration of inorganic phosphate and upon the type of sugar present in the culture medium.