ZYMOLOGY — FERMENTS AND FERMENTATIONS ' 229 



known and are called lipases, steapsins or lipolytic ferments. The best 

 known is the steapsin of the pancreas. It is very sensitive to the action 

 of acids and also to sodium chloride. Steapsin, like that of the pancreas, 

 is also found in the blood and in the liver of various mammalian animals, 

 even in fishes and in insects. 



Lipase is also found in the vegetable kingdom, as for example, in the 

 seeds of Ricinus communis and among the cryptogams as Aspergillus 

 niger and Bacillus fluorescens. It causes the decomposition of fats in 

 germinating seeds and in other fat bearing plant tissues and organs. 



6. Ammonia Forming Ferments — Urease. — These ferments act on 

 exposed urine changing it from an acid to an alkaline body, due to the 

 decomposition of urea into ammonium carbonate. The organisms that 

 form urease are not normally present in urine. They are widely distrib- 

 uted in the atmosphere, producing their characteristic changes in exposed 

 urine. Most of the urease forming organisms belong to the bacteria, as 

 Micrococcus urince and Bacillus urea. The latter is highly thermophilous, 

 begin capable of resisting a temperature of 90° C. Many other urine 

 organisms are reported, including cocci, bacilh and sarcinas. They are 

 all aerobic and require grape sugar, urea, phosphorus, sulphur, potassium 

 and magnesium for their growth. 



Certain bacteria are very active ammonia formers. A bacillus which 

 developed on shrimp and also on fish formed a sufficient amount of am- 

 monia to suggest the possibility of utilizing this organism in the com- 

 mercial manufacture of this gas. 



7. Lactic Acid Forming Enzymes. — ^Lactic acid is widely distributed 

 and is most important from the commercial viewpoint. It is the result 

 of the decomposition of a variety of sugars, induced by a great variety 

 of microorganisms belonging to the groups bacilli, cocci, vibiiones, and 

 sarcinae. AU agents which inactivate or kill the organisms named also 



"inactivate or destroy the lactic acid enzymes produced by them, as cold, 

 heat (above 60° C), disinfectants, acids, etc. 



In spite of the wide distribution of lactic acid in the animal and vege- 

 table kingdoms and the fact that a great many organisms are known to 

 form or liberate lactic acid, no lactic acid enzyme has as yet been isolated 

 or induced to act independent of living organisms. This has raised the 

 question, does a lactic acid forming enzyme really exist ? The presumptive 

 evidence however is decidedly in favor of the existence of such a ferment. 

 It is known for example that some of the lactic acid bacteria when grown 

 on a sugar free medium, for a long time, will when suddenly transferred 

 to a medium containing sugar, not have the power of forming lactic acid. 

 However, on prolonged culturing in sugar- containing media, this losf 

 power is graduaUy regained. This behavior may be explained on the 



