Published on December 21, 2016
1. Results 8.1 Disinfectants- Time of Contacts Disinfectants agent is a chemical drug that can kill bacteria especially vegetative bacteria. The growth of E. coli bacteria on nutrient agar plate which contain Dettol agent with different time of contact s shown in Diagram 1. From the diagram, there are heavy growth of bacteria with numerous of colony bacterial on the section of zero time, and there is moderate growth of bacterial can be seen on the 5’ minutes section whereas there no such growth on bacterial from 10-minute section to 45-minute section which there are none colony that can found. This can conclude that Dettol agent is act as disinfectants to kill all the E. coli bacterial in 10 minutes. 8.2 Disinfectants- Effective Concentrations Antiseptic is an agent that inhibits the growth of bacteria without destroy and killing it. From Diagram 2, there six tubes with different concentration of solution that Dettol agent mixed with saline which are 10-1 , 10-2 , 10-3 , 10-4 , 10-5 , 10-6 . Saline is a sodium chloride solution. Saline solution is an isotonic solution which contain concentrations of salt vary from low to normal to high. After 48 hours, the intensity of solution in tubes with 10-1 concentration is chalky colour, while the tubes with 10-2 and 10-3 concentration of solution is turns cloudy then the tubes with 10-4 , 10-5 and 10-6 concentration of solution is in slightly cloudy colour. This situation means that there is heavy growth of bacteria in solution of 10-1 tube, moderate growth of bacteria in the tubes with 10-2 and 10-3 concentration of solution and light growth of bacteria in the tubes with 10-4 , 10-5 and 10-6 concentration of solution. This is because serial dilution method decreases the concentration of E. coli bacteria in solution leads to the growth of bacteria decreases from 10-1 to 10-6 solution as the Dettol agent and saline are inhibits the growth of E. coli bacteria.
2. 8.3 Antiseptics- Zone of Inhibition Minimum inhibitory concentration (MIC) is meant that the lowest concentration of an antibiotic will stunted the growth of E. coli bacterial or calculate the zone of inhibition of bacterial. From Diagram 3, zone inhibition of Listerine mouthwash on E. coli bacteria which is 2 mm which is excluded the diameter of sterile disk which is 5mm and this is smaller than Colgate mouthwash which is 22mm. Thus the Listerine mouthwash is sensitive to the E. coli bacteria which is the zone of inhibition is smaller than 8mm is determined out Listerine mouthwash is effective against the E. coli. Whereas the Colgate mouthwash is resistant or ineffective against the E. coli bacteria as the zone of diameter is larger than 12mm. From Diagram 4, zone inhibition of Listerine mouthwash on sterile mouth swabs bacteria which is 8 mm which is excluded the diameter of sterile disk which is 5mm and this is larger than Colgate mouthwash which is 7mm after excluded the disk. Thus the Listerine mouthwash and Colgate mouthwash are sensitive to the sterile mouth swabs bacteria which is the zone of inhibition is smaller and equal to 8mm is determined out both mouthwash are effective against the sterile mouth swabs bacteria. Conclusion Antimicrobial agent are acts as inhibitor and destructor of bacteria. disinfectant agent is a strong agent to kill all the bacteria and antiseptic is an agent that inhibits the growth of bacteria. From experiment, we can conclude that effect of disinfectants are depend on the time of contact with bacteria which is Dettol agent killed all the E. coli in 10minutes. The concentration of E. coli bacteria in solution affect the effect o f disinfectants, the lower the concentration of E. coli bacteria in tube, the lower the growth of E. coli bacteria which is inhibit by disinfectants. Furthermore, the wider the zone of inhibition, the more susceptible the bacteria against the disinfectant agent. From the result of the zone of inhibition or the minimal inhitbitory concentration of disinfectant, Listerine mouthwash is sensitive to the E. coli bacteria whereas Colgate mouthwash is resistant against the E. coli bacteria. Lastly, Listerine mouthwash and Colgate mouthwash are sensitive to the sterile mouth swabs bacteria.
3. Reference 1. Books (a) Laboratory manual and workbook in microbiology eleventh edition Paul A. Granato, Verna Morton, Josephine A. Morello Pg85-90 (b) Prescott’s Microbiology 9th edition Joanne M. Willey, Linda M. Sherwood, Christopher J. Wolverton Published by Mc Graw Hill pg 742