110 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



and in their secretions, indicating that bacterial cells are as 

 dependent on enzymes for the production of their metabolic 

 activities as are higher types of cells, and that these enzymes are 

 not only present as intracellular constituents, but that they also 

 escape from the cells. 



The diffusion method of Wijsman, or, as it is more frequently 

 called, auxanographic method of Beijerinck, offers a relatively 

 simple means of detecting the presence of extracellular bacterial 

 enzymes. Eijkman l in particular has used this method, which 

 consists of mixing agar with milk, or starch, or whatever material 

 is to serve as the indicator of the enzyme action ; the agar is then 

 inoculated with bacteria and plated (or else the bacteria are inocu- 

 lated as a streak on the surface of the agar). About each colony 

 there will appear a zone of clearing in the medium, if it produces 

 enzymes digesting the admixed substance. By this means Eijk- 

 man found that all bacteria that produce enzymes digesting gela- 

 tin also digest casein, and those that do not digest gelatin are 

 equally without effect on casein ; therefore, it is probably the 

 same enzyme that digests both. As the hemolytic action of 

 bacteria is not constantly related to their gelatin-dissolving prop- 

 erty, the hemolysis probably is produced, at least in some cases, 

 by other means than the proteolytic enzymes. A few pathogenic 

 bacteria (anthrax, cholera) digest starch, and B. pyocyaneus, 

 Staphylococcus pyogenes aureus, and B. prodigiosus all produce 

 fat-splitting enzymes. B. pyocyaneus, he found, digested elastic 

 tissue readily, 2 as also did a bacillus resembling B. subtilis 

 obtained from the tissue of a gangrenous lung. The following 

 table by Buxton 3 gives an idea of the distribution of enzymes in 

 bacterial secretions as determined by the auxanographic method : 



ENZYMES HYDRATING CARBOHYDRATES 



Amylase. Maltase. Invertase. Lactase. Inulase. 



1. Anthrax + + 



2. Cholera + 



3. Coli communis 



4. Typhoid 



5. Diphtheria 



6. Staph. pyogenes aureus ... 



7. Lactis aerogenes + + 



8. Pyocyaneus 



9. Violaceus ... 



10. Mycoides + -f 



11. Prodigiosus 



12. Saccharomyces niger .... + 



13. Saccharomyces neoformans . . 



14. Aspergillus niger -f- -j- 



15. Aspergillus oryzoe -j- ~h 



1 Cent. f. Bakt., 1901 (29), 841. 



2 Cent. f. Bakt., 1903 (35), 1. 



3 American Med., 1903 (6), 137. 



