( 1201 ) 
0,05 KCl, 0,05 NH,Cl, and 2 to 4 drops of phosphoric acid, with 
aërobie cultivation at 20°-—25° C. The isolation of the fat-splitting 
yeasts is then effected by sowing the culture in which they are 
accumulated on yeast-glucose-gelatin with calcium carbonate, solidified 
in a culture box on a thin layer of fat. The colonies of the fat- 
splitting yeasts are signalised on this medium by their hydrolising 
the fat. 
Diffusing lipase is much more commonly secreted by moulds than 
by yeasts. Fat-splitting moulds can be best isolated from raneid fats. 
From the air, also, fat-splitting yeasts and moulds are obtained by 
exposing the said medium for some time to the air and subsequently 
isolating those organisms which have splitted fat under the colony. 
Fat-splitting bacteria, yeasts, and moulds, all secrete a lipase pos- 
sessing the same properties as shown by many experiments. 
Consequently, although the following researches are for the greater 
part carried out with lipase formed by bacteria, the thereby obtained 
results hold true as well for the lipase of yeasts and moulds. 
Formation of lipase by microbes in culture media 
of different composition. 
When fat-splitting microbes are cultivated in media of different 
composition, it is found that in media wherein they grow, also lipase 
is formed. 
Thus, B. lipolyticum, Oidiwm lactis, Torula, Penicillium glaucum, 
secrete lipase when cultivated in tap-water to which is added 0,05 °/, 
bikaliumphosphate, one of the following carbon sources: glycerine, 
glucose, calciumlactate, or natriummalate, ‘and one of the nitrogen 
sources : peptone, asparagine, ammoniumehlorid, or kaliumnitrate. 
The nature of the carbon and nitrogen sources is thus of no 
consequence for the formation of lipase by micro-organisms which 
assimilate them, that is to say, if a carbon or nitrogen source, what, 
ever be its composition, is assimilated by a fat-splitting organism, 
it will serve for the production of lipase by that organism. 
The composition of the medium, however, exerts its influence on 
the quantity of secreted lipase. 
By a certain number of microbes the greatest quantity of lipase 
is secreted when the culture conditions are the most favourable. This 
fact can be demonstrated in a simple way by a method with tubes 
coated with fat. 
Various substances, however, exert a retarding influence on the 
secretion of lipase by microbes, namely such compounds as sugars 
and alcohols, from which they form acids. 
ao 
Proceedings Royal Acad. Amsterdam. Vol. XIII. 
