Week 2: Single Colony Purification

Welcome back!

This week, we checked back on our plates of soil microbes from last week and determined the number of colonies on the plate. We had a good bit of diversity on our plates, and found many different types of microbes. To determine the microbes per gram of soil on our plates, we loosely counted (visually) the number of colonies on each plate, and factoring in the dilutions. For the plates that were diluted at 10^-6 and 10^-7, no colonies were found, so these plates will be omitted from the experiment. For the other plates, our microbes per gram as soil were as follows:

10^-3 Plate: 65,000 microbes/g soil
10^-4 Plate: 140,000 microbes/g soil
10^-5 Plate: 7,000,000 microbes/g soil
Rose-Bengal agar plate (10^-4 dilution):10,000 microbes/g soil

We found it odd that our more diluted 10^-5 plate had more microbes/g soil than our 10^-4 plate, but we determined that this could be due to a larger number of fungi growing on the 10^-4 plate; we only observed one visible colony on the Rose-Bengal agar plate, but we did notice on the regular 10^-4 plate that what was growing on the Rose-Bengal plate appeared to also be growing, in one large colony, on the 10^-4 plate, which could have prevented our 10^-4 plate from growing more microbes than our more diluted 10^-5 plate.

There appeared to be a very decent, if not large, amount of biodiversity from our soil. There were smooth and rough surface appearances on microbes; circular, irregular, and rhizoid colony edges; and microbes with flat and convex elevations. This variety in surface appearance, colony edge, and elevation implies that every microbe that looks different from one another is probably a different microbe. Not only that, even some of the microbes that looked very similar can also be different from one another and is not easily determinable from the human eye's perspective. The large amount of biodiversity in this small sample of soil can show us that the biodiversity surrounding us is massive and we don't even realize it.

So, why does biodiversity matter? Biodiversity is defined as the variety of life on Earth. This variety leads us to make new discoveries, utilize the naturally occurring elements around us, and take advantage of all that the Earth can provide to us to help us survive. The biodiversity on Earth matters because humans are all dependent on the benefits we receive from our environment - the air we breathe, the foods we grow, the animals we raise for food, the naturally occurring elements that help us find cures to diseases and to live healthier lives. Specifically in soil, soil microbes are important in Nitrogen-fixation, which is necessary for the growth of many important organisms including many of the plants and vegetables we eat. Soil microbes can also help break down organic matter that would not naturally break down, helping us to recycle many nutrients that would normally be thrown away. All of these these reasons for biodiversity show us that the earth is a fascinating, diverse, and complex place, and without the study of biodiversity and things such as soil microbes, we would not be able to take advantage of all that is naturally occurring around us and make advances in studies, especially microbiology.

See you next week!