Dry Soil Lab Report

1439 Words 6 Pages
A comparison of microbial growth in different soil samples reveals that microbes are more abundant and diverse in dry soil sample.

Microbes are the most abundant organisms on Earth, and they are easily found in soil. To determine and compare the abundance and diversity of several types of microbes between environments, two soil samples from different environments were gathered and compared. One sample was obtained from a hot, dry environment while the other was obtained in an area of dense foliage and animal traffic near a large pond. These samples were tested using nutrient agar for “simple” soil bacteria, glycerol yeast extract agar for Actinobacteria, and Sabouraud dextrose agar with antibiotic for fungi. For the first step, dilutions were prepared.
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In the arid soil sample, however, the calculations showed fungi to be the most abundant microorganism, which was not expected. Additionally, the total CFU/mL of the arid soil was much higher than the total CFU/mL of the damp soil, which was not expected. Finally, the observable diversity of the arid soil was much higher than that of the damp soil, which was not expected. Between both soil samples, some parallels were made. Both soil samples contained fungi as well as Actinobacteria that were described similarly. This suggests that, although the environments appeared to differ greatly, the diversity of both may not have been as different as expected. Several possible explanations for the unexpected results were proposed, and it was thought that human error was a factor. Dilutions may have been done without proper aseptic technique; plating may have been done without proper flaming or spreading; air contamination may have occurred; and counting may have been inaccurate, which would affect any calculations done. With a sample size of only six countable plates, the margin of error was smaller than

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