BIOL241 Final: BIOL241L - Final Exam Review
17 Dec 2015
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Document Summary
Experiment 1: direct microscopic count of microorganisms in milk. General information: slidebrite removes fat globules to make the cells visible, microbes in milk are composed of gram-negative, anaerobic rods. Examples: lactobacillus, micrococcus, streptococcus: microscope factor (mf) relates the field of view to the millilitre of or cocci milk. Calculate area of the microscope field in cm squared. Do 1 cm2 divided by the area to find number of fields in 1. Divide that number of field by volume of milk spread over 1 cm2 cm2 to get mf: advantages: results are rapid, minimum equipment required, disadvantages: dead cells mislead results, not accurate on low- morphologies kept. Results: pd-pasteurized > raw > fresh-pasteurized : in terms of cells per. Due to raw milk being sterile as it comes out: raw milk had both gram-positive and gram-negative rods and, pasteurization kills gram-negative so the fresh pasteurized had cocci ml of milk only cocci.
