The influence of the medium on the production of bacterial gelatinase

IN a previous communication [Haines, 1931] it was shown that bacterial pro- teases are produced by organisms growing in simple synthetic media made up from carefully purified substances, and the influence of salts of calcium and magnesium on growth and protease formation was discussed. The methods used to estimate protease formation, namely, liquefaction of gelatin as evi- denced by inability to set in ice-water and lack of coagulation of caseinogen on addition of acid, were however too crude to yield quantitative data as to the relative efficiency of the media in stimulating or inhibiting enzyme forma- tion. In particular, it is to be expected that small amounts of gelatinase will be formed on certain media, insufficient in quantity to cause entire liquefaction, which will escape detection by such a method. More sensitive ways of measure- ment were therefore sought, and changes in viscosity of a mixture of gelatin and enzyme seemed to offer a ready means of following gelatinase action.