Kristina SimonvicSection O24 Feb 2016Exercise SixTitle:Data Analysis from Hamburger Counts; Environmental Isolate StainingHypothesis:If the proper technique was performed when enumerating bacteria from the meat, then 30 to 299 colonies should be present on the plates.Methods:Count the number of colonies on each set of spread plates and pour plates. Plates that have 29 or fewer colonies are not statistically significant and should not be used in determining the titer. Plates that have much greater than 300 colonies are difficult to count as frequently a single colony was produced by two organisms that were very close together. Determine the titer for both spread plates and pour plates. This is done by dividing number of colonies found on a plate by the dilution. Record the spread plate and pour plate titers for your sample on the board. Record all of the class data and use the pooled results for writing your laboratory report. Continue microscopic examination of your environmental unknowns, including methylene blue, Gram stains, capsule stain and endospore stain. Examine to determine best storage conditions. Safety Concerns:1. Do not use plates with fewer than 29 or greater than 300 colonies when determining the titer2. Do not get oil on the 10 and 40 power lenses3. Wear safety glasses when working with stains4. Create a control when staining the environmental isolate5. Wash the environmental isolate stain horizontally instead of vertically Relevance:Determining the number of microorganisms in a sample is a routine and necessary procedure in
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