Greg Thomas
Mitch Thomas

Objective:

Our goal was to investigate the microbial concentrations at different points on a slope. We wanted to learn whether or not a slope made a difference in microbial action in comparison to a flat area of land.

Basic Outline For Procedure:

First, we had to search for an area to conduct research (a slope that was more steep than gradual.) After the slope was found, we then had to come up with a plan for collection of samples (procedure, time, etc.) So, we decided on taking samples from three different parts of a slope (top, middle, and near bottom.) The top level is labeled as point 3, the middle level has been labeled as number 2, and the bottom level was labeled as number 1. (This will be seen in results shown later in report.) We proceeded to do this two to four times per week, while varying time of day in which materials were collected in hopes of collecting the most accurate data. (We assumed that microbial action could vary during differing points of the day, so we collected at different times.) After collection, we would then plate and grow microbial populations (incubation for 24 hours at room temperature.) We would then count colonies and record on a data sheet, including differing colonies seen. Also, we ran soil tests of the specified area. This test reported the amounts of humus, potassium, nitrate nitrogen, and the pH levels. After 2 and ½ months of collection, we then analyzed data.

Each sample was taken from 1 inch under the surface of the specified areas. This was done to gain the best knowledge of microbial interaction. Also, this method is affective in collecting because it still allows for results in cold temperatures! Furthermore, samples were collected at same spot over the entire testing time. We placed sample in a prepared and labeled plastic bag. After collection, we would then proceed directly to the lab to insure optimum or most accurate results.

Sample Plating Procedure:

We encountered our first setback with this procedure. At first, we utilized materials given to us by the Biology Dept. that included a filter system, a pressure pump, plate and agar, and sterilized water (99ml). Well, we used this method for the first month. The first couple of trials we were getting no data, so we went to a microbiologist who informed us to try differing concentrations (dilution factors). So, we tried them over the next couple of weeks with no success. So, we came to the conclusion that the agar used probably did not support the growth of bacteria, or at least the bacteria we were collecting. As a result, we changed our method of plating, though we continued with the dilution factor of 10^-1. We utilized four different plates: EMB (Eosin Methylene Blue), Muller-Hinton, MacConkey, and Sabouraud. We used these to gain a variety of bacteria form the samples collected so that we could get the best results possible. After the first couple of trials, we discarded Muller-Hinton because it promoted the growth of uncountable numbers of bacteria because its nutrients could support so many differing types. The others promoted good growth but not too overwhelming for collection and analyzation. So, we did see results immediately after the switch of methods!

Other Experimental Setback:

After incubation and counting of colonies on each plate, we began to store in cold room between the two biology labs. But, this proved to be unsafe for our plates. They became contaminated and were rendered useless for further analysis.

After collection of numbers of colonies, we combined all data for each plate and averaged the number of colonies per plate per trial for better understanding of the information collected. In this instance, we found EMB to yield the results above. Two colonies appeared on this plate, dark purple and light purple. As one can see, dark purple growth was more dominant at each point of the slope. We also deducted that level 2 showed more of this type of growth, while levels 1 and 3 yielded approximately the same results.

From this plate, we obviously deduced that more growth was shown at the third level, top of the slope. This plate also yielded two types of bacterial growth, dark purple and light purple colonies. Again, one set of colonies prevailed over another (light purple.)

Our third type of plating was Sabouraud. From this plate we saw that there were two types of colonies, clear and white. We saw a distribution that was somewhat low and that was about even on all levels, although the second level had a little more yield of the white colonies.

After we analyzed the results of the three different plates, we could not come up with any distinctive conclusions. So, we decided to combine all the data collected from the different plates to see if anything could be deduced. We found that the third level had an overall yield that was higher than the other points of the slope. From this, we deduced that this finding could be attributed to the fact that point 3 was on the top of the slope, flat land. This land could be more stable than the others because it is not as susceptible to run-off as the others. The stability could have led to a greater concentration of microbial action.

Soil Nutrient Analysis:

We did a further analysis of the soil to see if there was any correlation between nutrients at different levels and the amount of microbial action. We found that levels were the same, except for the amount of humus detected. Humus at the third level seemed to be larger than at the other levels at the time of collection and analysis. So, we deduced that this higher concentration of humus could have resulted in the greater concentration of microbial growth and action. We also did research on soil concentrations to help us understand why humus might yield more action (www.statlab.iastate.edu/survey/SQI/sqw.html.)

We deduced that our findings were somewhat inconclusive because other factors needed to be considered to be accurate. For example, we felt that these factors needed to be considered: 1) Data from multiple sites is needed, 2)Long-term observation of these slopes is needed, and 3) Other environmental factors should be considered (e.g. seasons, temperature, rainfall, etc.). But, we did find that our results could lead to general theory which could be studied in the future. Our research gave us on hand experience that could be utilized in more testing. Also, our research showed us the difficulty in proving environmental theory because we understand that numerous factors shape the environment. Consideration of all factors is needed to be totally conclusive! Furthermore, we found that method was a huge part of research because faulty method could lead to no yield or faulty data! All in all, this was a great learning experience for us. We now better understand the methods and analysis tools used to do research in the field. The experience also heightened positive thinking about research because we actually researched and used our cumulative knowledge of biological systems!