Laboratory Outline for General Bacteriology 



Motility and flagella staining. Motility is determined from 

 day-old nutrient broth or agar cultures. Motile cultures are stained 

 for flagella. Preparations are made as follows: With a pipette 

 place about 4 drops of water together in a watch glass. Inoculate 

 center of water with culture taken from edge of growth in lower 

 part of agar tube. Be sure the needle is cool before starting and 

 avoid any rapid vigorous movements as the flagella are easily 

 broken off. Use enough bacteria to cloud the center of the water 

 slightly. Let the dilution stand for five minutes, then remove from 

 edge of dilution several loopfuls onto clean cover glasses. Do not 

 spread the loopfuls but let them dry on the several spots where 

 they were placed. The best flagella are usually found near the 

 edges of the drops. Air dry, and pass once through the flame. 

 Cover with freshly mixed mordant \/*> to 1 minute. Wash and stain 

 with carbol f uchsin 1/2 to 1 minute. Wash, dry, and mount. 



Sporangia and endospores. Determinations on these are 

 usually made from watery fuchsin stains from week-old cultures. 

 Sometimes, however, it is necessary to use younger cultures in order 

 to find sporangia. 



AGAR STROKE 



Agar medium is placed in test tubes and cooled in a slanting 

 position. This leaves a large surface. Inoculations are made in 

 one streak the entire length of the slanted surface, care being 

 exercised not to break down into the medium. For comparison 

 of growth at different temperatures two tubes are inoculated from 

 each culture. These are kept at 20 C. and 37 C. respectively. De- 

 scriptions are made at 7 and 14 days. 



GELATIN STAB 



Gelatin is used in tubes of about 10 mm. diameter. The depth 

 is about 4 cm. Inoculation is made with a straight needle stabbing 

 once in the center to the bottom of the tube. They are watched 

 to determine when liquefaction begins and is complete as well as 

 for the form of both liquefiers and non-liquefiers. Cultures are kept 

 30 days. 



POTATO CULTURES 



Potatoes cut in cylindrical pieces with a slanted surface are 

 sterilized in tubes having moistened cotton on the bottom to prevent 

 drying out of the potato. Inoculation is made in a streak up the 

 slanted surface. After incubation description is made in the same 

 manner and using the same terms as for agar slants. Records 



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