University of Texas at Austin BIO126L Course Instructor: Pratibha Saxena Spring 2009 Lab 5: Identification of organisms Purpose To learn the processes of biochemical testing to determine the identity of an unknown organism. Discussion Each of the eight biochemical tests helped determine a different characteristic of the organism. In narrowing down the possibilities for my unknown organism I first used the gram reaction and cell morphology (gram negative rods). Through these observations I could exclude half of the candidate organisms, leaving Alkaligenes faecalis , Pseudomonas fluorescens , Escherichia coli , Klebsiella pneumoniae , and Proteus vulgaris . I then observed the four carbohydrate fermentation tests. All of the carbohydrate fermentation tests were magenta in color and there was no bubble in the durham tube. The magenta color indicates that this organism metabolizes peptone rather than the
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