GENERAL BACTERIOLOGY lOl 



SECTION 9 

 . STUDY OF INTESTINAL BACTERIA 

 EXERCISE I 

 Make transfers from laboratory cultures of B. coli, 

 B. suipestifer, B. fecalis alkaligenes, and B. cloacae. 



EXERCISE 2 



In addition to the usual routine study prepare 

 fermentation tubes in the following manner: Meat 

 extract broth or meat infusion broth is inoculated with 

 a culture of B. coli to remove the muscle sugar and 

 incubated at 37° C. for 24 hours. The broth is then 

 boiled, the reaction made i per cent acid, and the broth 

 filtered until clear. Dissolve i per cent dextrose in 

 one third, i per cent lactose in another third, and i 

 per cent saccharose in the remaining third. Fill these 

 solutions into fermentation tubes and steriUze in the 

 arnold for three successive days. Any gas which accu- 

 mulates during sterilization in the closed arm must be 

 tipped out while the medium is hot. When cooled 

 down, inoculate the fermentation tubes with the four 

 organisms, incubate for 24 hours, and then measure the 

 gas in the closed arm. Replace in the incubator and 

 measure the gas again after 48 hours. Finally deter- 

 mine the composition of the gas as described on p. 81. 

 • In addition to the exercises outUned for this course 

 demonstrations should be made of stains of tubercle 

 bacilli in sputum, stains of diphtheria bacilU, methods 

 of anaerobic cultivation of bacteria, and various 

 outfits used in municipal laboratories for diagnosis. 



