42 STUDIES IN MICROBIOLOGY (2) 



Exercise VII 



EQUIPMENT 



Per student 



petri plate, sterile 



glass rod 



test tube, sterile 



agar plate (synthetic medium) 



bunsen burner 



2.3% nutrient agar (15 ml) 



2.3% nutrient agar plus 2500 units/ml streptomycin 

 (7.5 ml) 



2.3% nutrient agar plus 2500 units/ml penicillin 

 (7.5 ml) (the above three solutions all kept at 60°C 

 in water bath) 



E. coli: aerating culture (1 ml) 



S. marcescens: aerating culture (1 ml) 



S. marcescens: diluted saline suspension (10'* cells/ 

 ml) (1 ml) 



B. megatherium: about 10 mg/ml dry weight in 0.03 



M phosphate buffer, pH 7.0 (2 ml) 



B. megatherium: as above but in phosphate buffer 



containing 0.15 M sucrose (2 ml) 



lysozyme: 5 mg/ml in 0.03 M phosphate buffer, 



pH 7.0 (0.5 ml) 



Per 8 students 



marking pencils 



bacteriological loops 



slides and cover slips 



water in dropping bottle 



methylene blue solution in dropping bottle 



Per laboratory 



Ultraviolet germicidal lamp and safety glasses 

 Demonstration slides of S. marcescens and Pneumo- 

 coccus under phase contrast microscopes 



