PART III 

 APPLIED MICROBIOLOGY 



AIR MICROBIOLOGY 



EXERCISE 1. QUANTITATIVE BACTERIAL ANALYSIS 



OF AIR 



Apparatus. One carbon tube, dia. 15 mm.; cork stopper, 

 perforated, to fit carbon tube; short piece of glass tubing 

 bent at right angles; sand which has passed through a 150 

 mesh sieve; 8-liter aspirator bottle complete with rubber 

 stoppers and glass tubing; sterile test tubes * containing 

 10 c.c. of sterile physiological salt solution; sterile 1 c.c. 

 pipettes; four sterile Petri dishes; four tubes of sterile 

 agar for plating; sterile agar slants; tubes of sterile broth; 

 tubes of sterile litmus milk. 



Method. 1. Prepare a sand filter aeroscope by placing 

 a layer of cotton in the bottom of the carbon tube. 



2. Upon this place 1 cm. of sand which has been run 

 through a 150 mesh sieve. 



3. Insert a cork stopper through which is passed a bent 

 glass tube plugged at the outer end with cotton. 



4. Sterilize the apparatus in hot air oven. 



5. Place 8 liters of water in the aspirator bottle and 

 mark the level of this amount of liquid. 



6. Adjust the delivery tube so that it aspirates one 

 liter of air per minute. 



* For convenience in shaking the sample, it is recommended to use 

 test tubes with aluminum screw caps, having cork packing. 



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