072 BACTERIA IN ARTICLES OF FOOD. 



ferent bacilli, all of which are described in detail and none of which 

 were found to correspond with previously described species as given 

 in Eisenberg's Bacteriological Diagnosis. 



Peters (1889) has studied the flora of the "sauerteig" used in 

 Germany as yeast for leavening bread. In addition to the numerous 

 cells of three species of Saccharomyces, he finds that bacilli are present 

 in great numbers, as shown by direct microscopical examination and 

 culture experiments. He describes five species, designated Bacillus 

 A, B, C, D, and E, which are commonly present, and to which the 

 acid fermentation of the dough is ascribed. 



In Graham bread which had undergone changes making it unfit 

 to eat, Kratschmer and Niemilowicz have found the Bacillus mes- 

 entericus vulgatus, which appears to have been the cause of the 

 fermentation, which was produced in bread having a slightly alka- 

 line reaction by inoculating it with a pure culture of this bacillus. 

 The infected bread has a brownish color, a peculiar odor, and be- 

 comes sticky and viscid. 



Uffelmann (1890) has also studied the bacteria in spoiled rye 

 bread, and obtained, in addition to common mould fungi, Bacillus 

 mesentericus vulgatus and Bacillus liodermus. 



Waldo (1894) has shown that baking does not sterilize bread. 

 This was to have been expected in the case of the spores of bacilli, 

 but it is somewhat surprising to find that two species of Sarcina and 

 two micrococci survived the baking process. In all Waldo obtained 

 thirteen species of bacteria from the interior of sixty-two loaves 

 examined. Bacillus subtilis and allied spore-forming bacilli were 

 most frequently found, and the statement is made that a loaf " from 

 a low-class, dirty bakery will almost invariably contain more living 

 bacteria (or their spores) than .one from a good, clean bakery." 



Lehmann (1894) under the name Bacillus levans has described a 

 microorganism which closely resembles Bacillus coli communis. This 

 was obtained from sour dough, and was believed to be the cause of 

 the acid fermentation which so often interferes with success in ob- 

 taining sweet and wholesome bread. When a culture of this bacil- 

 lus was added to flour and water, without the addition of yeast, an 

 active fermentation occurred and the dough became acid. 



