Enzymes 35 



Plants and bacteria also possess their enzymes. 

 With the aid of these they are able to carry on their 

 life-processes. The different enzymes produced by 

 bacteria are numerous. Produced within the bacterial 

 cell, they may pass outward through the cell-wall and 

 attack the substances in the culture medium, which 

 serve as food for the organisms. Thus, in the case of 

 the cellulose ferments, the inert and insoluble fiber is 

 changed into sugar by the enzyme. The sugar, being 

 soluble, gradually passes into the protoplasm and is 

 used by the latter for the building of other substances. 



Pigments. — Intimately connected with the life pro- 

 cesses of bacteria is the ability of some species to produce 

 pigments. The coloring matters produced by different 

 species include golden yellow, orange, red, blue, pink, 

 violet, green, brown, and black substances. Blue or 

 red milk, and even bluish or yellow pus in wounds 

 may be produced by bacteria. 



The production of coloring matter is affected by the 

 food and the culture conditions. Temperature, likewise, 

 plays an important rdle in this relation. 



Phosphorescence. — The ability to produce phosphor- 

 escence is a property held by certain species of bacteria 

 in common with some members of the animal kingdom. 

 These bacteria, designated as photobacteria, are, so far 

 as is known, all inhabitants of the sea. The phosphor- 

 escence of sea-water, a phenomenon much commented 

 upon, is due largely, though not entirely, to bacteria. 

 It is these organisms, also, that produce phosphorescence 

 in decaying fish and meat. 



