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The Common Bacteria

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Bacteria are microorganisms that grow everywhere. Most bacteria in the environment will not be harmful. Therefore culturing bacteria is very easy and a simple way to test treatments. Culturing bacteria is the main way that new treatments are tested or in this experiment to compare treatments. Once the bacteria multiply into millions of colonies in a petri dish they become more hazardous. Bacterial colonies often cope with unfavorable living conditions such as the environment in Antarctica (Walters et al. 2002). To do so they have developed sophisticated modes of cooperative behavior. Such behavior causes bacterial colonies to exhibit complex growth patterns. Bacteria move in response to gradients in nutrient concentration and communicate with each other by means of chemomatic feedback. This allows the colony to respond efficiently to a wide range of growth conditions and generate self organization which is what a colony is (Campbell and Reece 2005).

Antibiotics are chemicals produced by bacteria that kill other unwanted bacteria. These chemicals inhibit or destroy bacterial growth. To determine if an antibiotic is effective in treating bacterial growth. The zone of inhibition should be measured and compared to a control or compared to another trial of the same antibiotic. If bacteria are susceptible to an antibiotic, a clear zone will appear around the disk (antibiotic) where the growth has been inhibited. Antibiotics are now harvested and unfortunately over the years antibiotics have been and still are overused and the bacteria are starting to mutate and develop new strains to resist the antibiotic (Levy 1992).

Finding new antibiotics is an ongoing process. Homeopathic remedies are considered to be non effective, but it depends on the person. Some of the remedies used are garlic, zinc and Echinacea. The natural remedy only works in some people and the conditions in which it is used (Greene 2000). In this particular experiment my null hypothesis was: There will be no difference in the zone of inhibition between the control and the treatments. My alternative hypothesis was: There will be a difference in zone of inhibition between the antibiotics and homeopathic remedies because the homeopathic remedies only work on certain people and conditions.


Four sterile nutrient agar plates were obtained and labeled garlic, echinacea, zinc and control. One group member swapped the back of her mouth with a sterile swab then swabbed the bottom of the agar plate covering the entire surface. This was done for each plate and a new sterile swab was used each time. Filter paper was hole punched out into a petri dish. Forceps were sterilized by wiping it with an alcohol pad, then three filter paper circles were put into each of the treatment plates, then one drop of the appropriate treatment was put onto the three filter paper circles. Another plate was obtained and was swabbed by the same person as before. The teaching assistant dispensed eight antibiotic disks on the plate. The antibiotics used were; Penicillin, Tetracyline, Neomycine, Kanamycin, Gantamycin, Erythromycin, Cephalothin, and Ampicillin. All of the plates were then wrapped with parafilm around the side of the plate so that we could get a clear view without opening the plate. All the plates were turned upside down and stored at for one week for an incubation period. The plates were then examined for the zone of inhibition then the diameter was measured with a ruler in millimeters. The five inhibition zones for each were averaged for the homeopathic treatment. Each antibiotic disk zone inhibition was measured the same way but was not averaged because only one disk per antibiotic was used. All the data was recorded was written down and reported to the teaching assistant so a class average table could be created.


I found in Table-1 there was a large range of measurements for the zone of inhibition. The size of the zone inhibition ranged from 0-28mm depending on each treatment that was examined. Figure 1 shows the differences in the size of the zone of inhibition between homeopathic remedies and antibiotics in terms of class average. The homeopathic remedies have a lower class average than the antibiotics. The homeopathic remedies average ranges from 3.8 to 5.9. Garlic was the highest with 5.9 and Echinacea being the lowest with 3.8. Antibiotics are noticeably more effective than homeopathic remedies. They ranged from 0 to 22. Neomycin was the lowest (0) and Penicillin being the highest with 22.


My alternative hypothesis is accepted in this case, because there was a difference in the size of the zone of inhibition between homeopathic remedies and the antibiotics. Therefore my null hypothesis was rejected because there was a difference in inhibition zone sizes between control and the treatments. For example

The inhibition zone is the area where no bacterial growth has occurred. It is usually around the treatment and is circular in shape. Each zone of inhibition is different because each treatment behaves differently toward the bacteria (Schmidt). The data in Table-1 shows the different sizes of the zones of inhibition of each of the treatments. The results obtained are not very accurate in my own opinion because there are a handful of variables that could affect them

There are a number of possibilities



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