Effects of physical, chemical and biological agents on bacteria Experiment 4

Outline Moist heatUV Chemical &biological agents Bacteria E.coli B.subtitis S.aureus E.coli Culture media BrothAgar plates Equipments Water bathUV light - Reagents Non 2% iodine 1% crystal violet 2% mercurochrome garlic paper disks of penicillin paper disks of streptomycin

 Effect of moist heat BacteriaE.coil (liquid) (shake it)B.subtitis (slant) Temperature 100 ℃ RT 100 ℃ RT Time5min30minControl5min30minControl Tube number1#1# 2#2# 3#3# 4#4# 5#5# 6#6# Stand A Stand A Stand B Stand B Stand C Stand C 4 students / group

 Effect of UV light Condition ： expose UV light for 30min Bacterial strain ： S.aureus Inoculation method ： Streak plate (with cotton stick) UV 30min UV mark

 Effect of chemical and biological agents Reagents: 1. 1% crystal violet 2. 2% mercurochrome 3. 2% iodine 4. garlic 5. paper disk of penicillin 6. paper disk of streptomycin Species ： S.aureus 1 agar plate E.coli 1 agar plate MarkManipulation Bring with me tomorrow ！

 Part 1. Effect of moist heat on bacteria; E.coli, B.subtitis  Part 2. Effect of UV light on bacteria; S.aureus  Part 3. Effect of chemical & biological agents on bacteria; E.coli, S.aureus Observation of results

Moist heat  E.coli 1 # : 100 ℃, 5min 2 # : 100 ℃, 30min 3 # : RT, Control  B.subtitis 4 # : 100 ℃, 5min 5 # : 100 ℃, 30min 6 # : RT, Control

Strains 100 ℃, 5 min 100 ℃, 30 min Control E. coli B. subtitis Record: Effect of moist heat on bacteria  Clear: “-” or bacterial growth: “+”  Surface growing / Turbidity / Precipitate growing;

UV radiation  Covered part  Radiated part UV Describe result:

Effect of chemical and biological agents  Measure inhibition zone diameter or 2  radius

Effect of chemical and biological agents Inhibition zone diameter (mm)>15mm10~15mm<10mm 0mm susceptibility degree Extremely sensitive Medium sensitive Slight sensitive Resistant Cultures Diameter of Inhibition Zone (mm) 1% Crystal violet 2% Mercurochrome PenicillinStreptomycin2%IodineGarlic E.coli S.aureus Susceptibility degree Record: