Biology 1A03 LAB ASSIGNMENT

Biology 1A03 LAB ASSIGNMENT - Biology 1AO3 Biology Lab...

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Biology 1AO3 Biology 1AO3 Lab Three: Lab Three: Microbiology and Efficacy of Different Antibiotics Microbiology and Efficacy of Different Antibiotics Date of Lab: 4 November 2010 Date of Submission: 11 November 2010
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Abstract In this laboratory lab, the treatment of water samples is tested on by antimicrobial agents to analyze the effectiveness of treatments. In part A, through serial dilutions of the untreated water sample and the treated water sample, the colonies of bacteria left can be observed in agar plates, the calculation of the concentration of the bacteria per milliliter of a sample in both, control and treatment, can be compared. It has been observed that bacterial colonies in the least concentrated treatment are significantly less than the bacterial colonies in control. In Part B of the lab, four different antibiotic discs are placed in each of the plates of E. coli, M. luteus and untreated water sample. After 24 hours of incubation, the amount of clearing was exhibited an thus, the gram positive and gram negative nature of the lawns were observed. Gram +ve and gram –ve are differ in which antimicrobial treatment is more effective when the zone of inhibition is measured. Introduction: Untreated water can turn into a deadly case, and measures must be taken to treat it. The issue is to measure the approximate number of bacteria contaminating a water sample, and suggest an experiment that contributes to the reduction of microbial contamination in the water. Using the technique of serial dilution, the bacteria can be counted in a contaminated solution with the naked eye. The untreated water is mixed with a large amount of saline, called a diluent. Then, a series of 10-fold dilutions of the original mixed fluid is carried out a number of times. Serial dilution is important because the experimenter can use the culture plates that produce countable numbers from the different dilutions to calculate colony-forming units per millileter of the sample, as well as how many bacteria in total were present. The treated water sample with the least concentration is expected to exhibit the least amount of bacterial colonies and opposed to the lesser diluted samples. In this laboratory experiment, the treatment used in part A is sodium hypochlorite or bleach. Sodium hypochlorite has a lot of uses and is an excellent antimicrobial agent. . Since it is strong oxidizer, it works by denaturing a bacteria’s proteins causing insoluble aggregations, and clumping of proteins. This leads to loss of proper function of essential bacterial growth, and the cell eventually dies. This will show how many cells of the colonies are still alive in the treated water samples and compared to the untreated water samples.
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Antibiotics can be selective; some are non-toxic to plants, animals and unstimulated bacterial cells, but are toxic to bacteria that are being reproduced. There are four ways that antibiotics can inhibit bacterial reproduction; since bacterial cells have a cell wall are composed of murein that is important for structural
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This note was uploaded on 12/05/2011 for the course BIO 1A03 taught by Professor Kajiura/boreham during the Spring '11 term at McMaster University.

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Biology 1A03 LAB ASSIGNMENT - Biology 1AO3 Biology Lab...

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