Bacterial growth patterns and the effects of environmental factors on properties of colonies ERIC Al Abstract In this experiment we work with different types of bacteria and experiment with their different properties and how they grow in certain situations. Different samples of bacteria cultures were gathered from different places such as the mouth, shaded mulch, and from the table top.
The samples were collected by using a cotton swab and swiped onto a Petri dish filled with nutrient agar. The bacteria were then left to grow on their own in a relatively well shaded area.As a control, a cotton swab that had nothing on it was used. It was recognized that different types of bacteria exist in different environments and grow in different ways compared with one another. As was discovered, the human mouth generally holds brightly colored bacteria varying from red to yellow that grow in a disc shape with no discernible repetitions or rings while other areas such as table tops and dirt had more darkly colored cultures forming in alternating rings of light and dark brown or gray.
In addition, given the time available to grow, the average culture grew to a size of 1 CM in diameter ranging from 0. To 1. 4 CM. Most cultures were found to be circular in shape thus implying constant growth in all directions. Knowing the different types of growth patterns will allow future doctors and medicinal practitioners to better know how to recognize certain bacterial growths and infections.
Introduction In the field of medicine today discerning different bacterial infections from one another is an important technique for doctors and medical practitioners. The difference in growth patterns of bacteria allows scientists to distinguish different cetera from one another, especially when symptoms of infections are unclear.The experiment also gives information on how to control bacterial growth in the case of developing antibiotics and other medicines. The method of collecting bacteria using a cotton swab or a similar apparatus and then transferred on to the growth medium has been widely used in measuring growth curves in certain mediums such as lake water (Transit and H¶feel 1987), filming bacterial growth (Bruno and Venezuelan 2012), and measuring bacterial growth efficiency (Giorgio and Cole 1998).Although many scientists use the process of incubation in order to speed up their experiments, bacterial growth is not inhibited if an incubator is not used.
In fact, incubation may adulterate results due to extremely low frequency (ELF) magnetic fields being present while incubators are used (Mild 2009). There are 5 different types of bacterial growth patterns?high nutrient level with a hard, semi-soft, or soft medium and low nutrient level with a hard or soft medium (Lasts 1999).In this experiment we focus on the different growth patterns of bacteria in a high nutrient level with a semi-soft to soft medium. In this way most of our cultures will appear as concentric rings or discs. In addition we know that the most abundant forms of mouth bacteria are colored orange, yellow, purple, or are colorless.
However, we will be unable to predict the colors of bacteria gathered from mulch or faucets. While performing the experiment, I expected my swabbing technique would gather more than one type of bacteria thus allowing for more bacterial diversity which would give me a larger sample size.Therefore in general we expect many discs and concentric rings along with bright colors for mouth bacteria along with darker lord bacteria for any other areas that we gather from because the mouth is such a specific environment that only highly specialized bacteria will survive there, thus allowing us to infer that most other bacteria will be darker colors. Materials and methods Materials A batch of pre-prepared nutrient agar will be necessary for a medium in which the bacteria can grow.Nutrient agar can be made by mixing beef extract, potent, and agar in a saucepan. Increase the mixture to a boil and allow it to cool until it is warm, then poor it into the Petri dishes (McKesson 2008).
Allow the ashes to cool in a refrigerator before using them. In addition to nutrient agar, Petri dishes were used to hold the nutrient agar and cotton swabs were used in order to gather the bacterial samples. Aside from that, dark areas will be required for either bacterial samples or a place to store the bacteria cultures as they grow.Experimental setup In order to effectively perform the experiment, it will require very sterile conditions where the bacteria cultures grow along with sterile and controlled gathering of bacterial samples. Gather your samples with a cotton swab and be sure to to let any surface come in contact with the cotton swab other than the surface used to gather the bacteria. In order to reduce contamination by bacteria in the air, avoid opening the Petri dish until your cotton swab is ready.
Moreover, make sure your nutrient is extremely hot when it is poured into the Petri dish so as to kill any preexisting bacteria. Although the basic setup of the experiment is simple, avoiding any forms of contamination is difficult. Simple procedures such as washing hands and wearing latex gloves will greatly improve the accuracy of your results while completing this experiment. Gathering results The results from this experiment will be mainly qualitative although it is possible to measure things such as average size of the bacterial cultures given the amount of time they had to grow.Using a ruler, you have the ability to measure bacteria length and width, possible bacteria depth (most cultures will be too thin for this to be a possible piece of data), as well as bacteria diameter (if cultures are mostly circular).
Noncircular bacteria should generally be measured the longest span by the shortest span (length by width). Qualitative data should consist f at least 2 groups. The most important group in the case of our experiment will be color due to the fact that we know the general shape of our cultures already. Generally if color varies greatly between cultures, a less detailed description of the color is acceptable.
However, if the colors are very similar, a more detailed description of the colors will be required. The second group of qualitative data is the shape of the bacteria culture. For this specific experiment we only have two possibilities; however outliers may increase that to 3 or 4 possibilities in the shape roof of data. Generally you will get either concentric circles or discs depending on the consistency of your nutrient agar. Figure 1 An example of necessary materials Results Quantitative Data The average length by width of the bacterial cultures was 1.
025 CM by 1. 045 CM.It seems that on average most bacterial cultures are circular in shape and given the time they had to grow, were able to reach a relatively large size. On average however, the bacteria cultures gathered from the mouth were smaller than those gathered from mulch or more dirty areas by about 0. 3 CM. This was probably due to the innate cleanliness of the mouth due to constant cleaning.
Qualitative Data There was an almost even distribution of disc and concentric ring growths. However in the bacterial cultures from the mouth were all disc growths while the cultures from dirtier areas were all concentric rings.In addition, it was observed that all samples that were collected from the mouth were brightly colored, ranging from yellow to orange. On the other hand, samples taken from dirtier areas tended to have a more earthen color ranging from tan to dark brown. After the given mount of time for bacterial growth, smaller white spots began to grow on the plates. Although they grew after the allotted time frame for the experiment, they provided an interesting note that fungus-like growths have the ability to proliferate on Petri dishes.
In addition to predicted results, it was found that samples gathered from dirtier areas produced a yellowing colored waste that changed the color of the nutrient agar. This seems to indicate that the available nutrients for the bacteria in this culture is running low due to the huge number of bacteria that are growing there. Conclusion My hypothesis before carrying out this experiment was that the dirty bacteria would be very dark colored while the mouth bacteria would be more brightly colored due to previous research.In addition I predicted all of the cultures to grow in disc-like growths due to the fact that I believed the nutrient agar to be considered soft mediums. However it turned out that the concentration of nutrient agar made the medium semi-soft in some cases which produced concentric ring growths.
As for my hypothesis on the size of the colonies, I predicted most of them to grow to about 0. CM with no particular reason other than a guess that there wouldn't be enough time to grow. However the colonies ended up all growing to about 1 CM in width and length which surprised me.Width vs.. Length 1.
5 Length (CM) 1 0. 5 000. 5 1 Width (CIT) 1. 52 Figure 2 Graph of width vs..
Length in bacterial cultures Figure 3 Three examples of bacteria cultures Discussion Error Analysis There seemed to be a couple of very prominent errors that plagued my experiment. The most obvious error seemed to be contamination. Many of the Petri dishes used became contaminated eventually. It would have been better o keep check of possible contamination factors by wearing gloves when gathering bacteria samples and handling the Petri dishes.In addition, it would have been good to avoid opening the Petri dishes or moving them around too much unless I was collecting samples.
Aside from contamination, other possible factors could have been the amount of nutrient agar in each dish and how concentrated it was. This may have either stunted or increased bacterial growth, thus adulterating any results. Scientific Significance The specific bacterial growth patterns of certain types of bacteria have already been recorded; however there are still many patterns that have yet to be discovered.In general bacteria growth patterns can be limited to 5 different categories. The results shown in this experiment allow scientists to diagnose people with throat infections due their knowledge of the types of bacteria that exist in a person's mouth. In addition, the results will allow for further categorization of bacterial growth patterns and how they are limited by their environments.
As the data shows, bacteria will generally have a constant rate of growth if they are in the name environment even though they differ from one another.Not only that but we can observe that as bacteria grow, they transition from a more circular growth into an amoeba-like growth. This information will mainly be used in the medical field to continue research in controlling bacteria and their growth along with giving doctors another option in diagnosing their patients. Figure 4 3 Mouth bacteria Works Cited Bibb, Basil G. , and George Parker Berry.
"A Cultural Study of Filamentous Bacteria Obtained from the Human Mouth. " Journal of Bacteriology 38. 3 (1939): 263-74. US National Library of Health.
