Effects of Tetracycline and Kanamycin on Pseudomonas fluorescens

Naomi Drake, Mary Powell, Alexis County

Low Down

• Question: Which antibiotic, Tetracycline or Kanamycin, has the greatest effect on the lag phase of Pseudomonas fluorescens?

• Hypothesis: The organism’s lag phase would be more significantly extended in the presence of kanamycin as opposed tetracycline.

0:00:00 12:00:00 24:00:00 36:00:00 48:00:00 60:00:00 72:00:000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6Effects of Tetracycline on the Lag phases of P. fluorescens

Dilution 1:1000Dilution 1:10,000

Time (hours)

OD

Initial growth: Dilution 1:10,000- reached .4 OD @ 9:45:05 hours [.392, .443 @ 10:00:05 hours]

Extended Lag phase: Dilution 1:1000- reached .4 OD @20:00:05 hours [.394, .422 @ 20:15:05 hours]

Note: Dilutions 1:10 and 1:100 fully inhibited growth

0:00:00 12:00:00 24:00:00 36:00:00 48:00:00 60:00:00 72:00:000

0.2

0.4

0.6

0.8

1

1.2

1.4

Effects of Kanamycin of Lag phase of P. fluorescens

Dilution 1:1600Control

Time (hours)

OD

Initial growth: Control (no antibiotic)- reached 0.4 OD @ 4:30:05 hours [.397 OD, .424 OD @ 4:45:05 hours]

Extended Lag Phase: Dilution 1:1600 – reached 0.4 OD @ 28:30:05 hours [.398 OD, .412 OD @28:45:05 hours]

Tetracycline vs Kanamycin

Conclusions

• Based on the data collected, P. fluorescens is resistant to tetracycline in various dilutions ranging from 1:10 to 1:12,800.

• In the presence of Kanamycin however, the bacteria was susceptible, in varying ratios, ranging from dilutions 1:2 to 1:12,800.