274 ENZYMES OF BACTERIA 



which hydrolyze fructosides, such as sucrose, raffinose, gentianose, and stachyose; 

 the a-glucosidases, which hydrolyze maltose and trehalose; the /3-glucosidases, which 

 act upon cellobiose, gentiobiose, and others; galactosidases, acting upon lactose and 

 melibiose. 



The various carbohydrases are produced abundantly by bacteria and other micro- 

 organisms. However, considerable specificity exists among the enzymes of different 

 organisms. Cellulase is produced by very few groups of bacteria, namely, those which 

 are capable of utilizing complex celluloses as sources of energy; this is an endoenzyme, 

 although it may also diffuse outside of the cell.^ Hemicellulase or cytase is distributed 

 more abundantly, due to the fact that many more types of bacteria are capable 

 of attacking hemicelluloses and utilizing them as sources of energy. However, 

 neither of these enzymes can be obtained in any great abundance from bacterial 

 cultures. 



Amylase (diastase) is produced both by a greater number of organisms and in 

 considerably larger amounts. It is sufficient to mention the bacteria of the B. siibtilis- 

 mesentericus group, which are even utilized for producing the enzyme on a commercial 

 scale. B. anthracis, B. tuberculosis, V. cholerae, pyogenic streptococci, etc., B. coli, 

 B. pneumoniae, and various other bacteria produce only traces of this enzyme.^ This 

 enzyme can be best demonstrated by growing the bacteria upon a starch agar plate, 

 then covering the plate with a dilute solution of iodine in potassium iodide. 



Gelase is produced by some bacteria.^ Pectinase is produced by B. carotovorus 

 and other bacteria. 



Saccharase or invertase is produced by various bacteria, including B. subtilis, B. 

 mesentericus , B. megatherium, B. fluorescens, B. pneumoniae, hemolytic streptococcus, 

 butyric acid bacteria, etc. The most important source of invertase among micro- 

 organisms is found, however, among the yeasts. Maltase and lactase are also pro- 

 duced by a number of bacteria. These also are formed in greater abundance by yeasts 

 and fungi than by bacteria. Emulsin formation has been demonstrated for a number 

 of bacteria,^ especially among representatives of the colon-typhoid group. The prop- 

 erty of forming this enzyme is frequently utilized for the specific differentiation of 

 bacteria. In the decomposition of glucosides in various natural fermentations (indigo, 

 flax, etc.), bacteria play a prominent role. 



Nucleases, or the group of enzymes which hydrolyze the nucleic acids, are also 

 found among the bacteria.^ 



The decomposition of the protein molecule to its simplest constituents is carried 

 out by three distinct groups of enzymes, namely, (i) the proteases, which hyrolyze 

 true proteins to proteases and peptones; (2) the peptidases or ereptases which hydro- 



' Kellerman, K. F., McBeth, I. G., Scales, F. M., and Smith, N. R.: Centralbl.f. BakterioL, II, 

 30, 502. IQ13; Pringsheim, H.: Ztschr. f. phys. Clieiiiic, 78, 226. IQ12. 



^ Fermi, C: Ccntralbl. f. Baklrn'oL, 12, 713-15. i8q2; ibid., I, 40, 1S7. 1905. 



^ Biernacki, W.: //'/</., II, 29, 166. igii. 



^ Weintraub, A.: //)/(/., I, Orig., 91, 273. 1924; Fermi, C, ami Montesano, G.: ibid., 15, 72.' 

 1894. 



5 Schittenhelm, A., and Sthroeter, F.: Ztschr. f. phys. Chemie, 39, 203. 1903; 40, 62, 70; 41 

 284; 57, 21. 1908. 



