Antimicrobial Activity of Soil Isolates

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Antimicrobial Activity of Soil Isolates


Isolation and characterization of microorganisms is a practice that aids in

Increasing ones knowledge of a laboratory setting and it helps improve on

Using sterile technique. Isolates of soil microbes can be categorized and

Characterized based on a number of criteria ranging from gram-staining

Which is done for this project to enumeration which is quantitative description

Based on the amount of microbial colonies available. The Antimicrobial

Activity of three different microbes were also tested and results were obtained

For two out of three of the microbes. Two out of three of the tested microbes

Exhibited antimicrobial activity towards the bacteria E. Coli and B. Mycoides

And the results were recorded. Microbes produce various antibiotics and by

Isolating different microbes the antibodies can be tested for.


This lab focuses on the isolation and characterization of an unknown organisms expressing interesting properties in relation to Antimicrobial Activity. At the conclusion of this laboratory experience The researcher would be required to describe the isolates obtained from the soil macroscopic and microscopic appearance, Perform the gram stain of the microorganisms in question and to discriminate the organisms from other microbes that could be contained in the soil and to finally make certain that the organisms have not been exposed to outside sources and be isolated in a pure culture. The researcher must first isolate the microbe and try to grow the organism in a pure culture to commence with testing the organism. The isolation of Microbes in a laboratory and clinical settings are of the up most importance and due to the isolation of different microbes from each other various procedures become open for the researcher to use like six fold dilutions that allow for the quarantined microbe to be reduced down in number to ensure that the test are being run are being tested on just a single type of organism. But before dilutions can occur the microbe must first be liberated from the soil and streaked onto an Agar plate to grow. There are various methods that can be used once the organism has grown onto the agar plate to ensure that the sample collected would o...

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...actors due to the large or small amount of colonies present on my agar plated media. This could be accounted for by stating that there was a very large amount of microbes present in the soil and the dilutions did not dilute enough of the microorganism out or human error could also account for Not having any statistically significant plates to use.

The bacterium that I replated was obtained from the YPD 10-3 media and it gave rise to bacterium 1 & 3, The other bacterium that I obtained came from LB 10-5 . The two bacterium from the YPD plate varied in color the bacterium that I refer to as one had a reddish color had a circular form a raised elevation and a entire margin, The bacterium that I refer to as 3 Had a grey appearance a circular form a raised elevation and the margin appeared to be entire. The bacterium that I obtained from the LB media had a white appearance had a circular form a faintly raised elevation and the margin was entire.


-Microbiology Laboratory Manual

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