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A Investigation to measure the effect of different anti-microbial compounds on bacterial Growth

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Introduction

A INVESTIGATION TO MEASURE THE EFFECT OF DIFFERENT ANTI-MICROBIAL COMPOUNDS ON BACTERIAL GROWTH PLAN Aim The aim of this investigation is to see whether the different anti-microbial substances effects the growth of bacteria at different dilution's. Prediction All the anti-microbial solutions will create large clearance zones at the undiluted level, but the clearance zones will decrease as the solution becomes more diluted. Variables Incubation temperatures at which the experiments are done are kept constant. The same bacterial culture is used. The same nutrient agar is used. INTRODUCTION Variables Incubation temperatures at which the experiments are done are kept constant. The same bacterial culture is used. The same nutrient agar is used. Apparatus Bacterial Culture Bunsen Burner Heat Proof Mat Tweezers 6 Sterile Petri dishes 6 x 15cm3 of molten nutrient agar Three different antiseptics (1)Dettol (2)TCP (3)Savlon Three different disinfectants (1)Dettox (2)Domestos (3)Vortex Sterile water for dilution 18 Sterile Universal Bottles 24 x 0.5cm diameter filter paper disks. Background About 200 species of bacteria are pathogenic, or disease causing, for humans. Pathogenicity varies widely among various species and is dependent on both the virulence of the particular species and the condition of the host organism. ...read more.

Middle

The petri dish should be marked on the underside with the dilution's of the anti-microbial solution in the areas that they have been placed. The completed dishes are labelled with the name of the anti-microbial solution and should then be put in an incubator at 25oC in the upright position for 24 hours. After this time, by measuring the diameter of the clearance zone (in mm) the effectiveness of the anti-microbial solution can be assessed. This procedure should be repeated a further 2 times so an average diameter of the clearance zone can be obtained. RESULTS Antibacterial Agent Dilution Dilution Dilution Dilution 0 x 5 x 10 x 100 Dettol 9 8.3 7 5.7 TCP 10.7 8.3 6.7 4.7 Savlon 6.7 5.7 5.7 4.7 Dettox 9.7 8.7 5.3 3.7 Domestos 15 14.3 10 7 Vortex 14.3 13.7 9.7 5.7 To measure the diameter of the clearance zone the filter paper discs had to be removed. CONCLUSION / EVALUATIONS AND LIMITATIONS The aim of this investigation was to see whether the different anti-microbial substances affected the growth of bacteria at different dilution's. The graphs show that the growth of bacteria is affected by anti-microbial substances, even at very low concentrations (x 100) ...read more.

Conclusion

Graphs 2, 3, 4, 5, 6 and 7 all show the exact diameter of each clearance zone at the different dilution's of the different solutions. In graph 4, there is an anomaly. At concentrations x 5 and x 10 the Savlon appears to have the same diameter of the clearance zone. This shows that at these dilution's there is no difference in the effectiveness of this solution. But this may have been caused by a miscalculation of the mean or my the miss-reading of the clearance zone with the ruler. The two concentrations may have been mixed up and one concentration may have been used for two sites of bacteria on the agar plate. The results show that there was a difference in the effectiveness of the different anti-microbial compounds that were used to inhibit the growth of bacteria. The investigation in general was too vague. Only the clearance zone of one type of bacteria was measured, while the amount of carbon dioxide produced could have impeded the growth of the bacteria. The amount of oxygen available to the bacteria was not measured. Another factor that could have been limiting may not have been measured. If more factors were considered then the experiment could have been made fairer. ...read more.

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