DISEASES OE CHEESE 



141 



Bitter cheese is due to a variety of bacteria, as Tyrothrix 

 geniculatus (the bitter soft cheese bacillus), Micrococcus casei amari 

 (bitter cheese coccus), Weigmann's bitter milk bacillus, Conn's 

 bitter milk coccus, and others. Red coloration of cheese may be 

 caused by yeasts {Saccharomyces ruber) or by cocci. Black cheese 



Fig. 45. — Oidium lactis. a, b, Dichotomous branching of growing hyphffi; c, d, g, 

 simple chains of oidia breaking through substratum at dotted line x-y, dotted por- 

 tions submerged; e, f, chains of oidia from a branching outgrowth of a submerged 

 cell; h, branching chain of oidia; k, I, m, n, 0, p, s, types of germination of oidia under 

 varying conditions; t, diagram of a portion of a colony showing habit of Oidium 

 lactis as seen in culture media. — [From Bull. 82, Bur. Animal Industry, V . S. Dept. 

 Agr.) 



may be due to the presence of iron in milk, perhaps traceable to the 

 action of slightly soured milk in rusty buckets. Some yeasts and 

 molds may produce dark to black decomposition changes. Blue 

 cheese is the result of the action of a bacillus. Putrid cheese is the 

 result of the invasion of saprophytic bacteria and other micro- 



