BIOL241 Final: 241 lab note summary
30 Jun 2015
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The typical microbial population in milk: gram- positive (ge+), nonmotile, microaerophilic or aerobic rod. Generation: lactobacillus, micrococcus, streptococcus. The use of slidebrite: it is used to remove the fat globules. Direct microscopic count: rapidly to get the result. Advantage: minimum equipment needed, counted the clumps and individuals, can make permanent records. Different to make difference between the cell and debris. The average # of cells per field x microscope factor (field/ml) Colony counts from various dilutions x dilution factor. Genera in cheese: (lactic acid- producing bacteria) streptococcus, lactobacillus. Gas formation (gas- producing organisms): clostridium, coliform bacteria (e. coli and. Spoilage (dairy mold): geotrichum, cladosporium, penicillin. Comparison of the 3 agars. Expected results many organisms, most lactic bacteria coliform: green sheen. Enterobacter: pink colony (fish eye) 30 for 1- 2 days 37 for 1- 2 days. Fungi- green opaque filamentous colonies. Low ph (5. 4) and increasing sugar level in the agar in order for fungi to grow.
