Microorganism Lab Report

Purpose:
To identify an unknown microorganism by performing a series of biochemical tests on a pure bacterial culture.
Materials and Methods:
Tests:
Lactose fermentation: Fermentation makes energy available for use by microorganisms by anaerobic breakdown of carbohydrates. The product can either be an acid or gas. When it is positive, the broth will turn from red to yellow and if gas is present a bubble is formed.
Sucrose fermentation: This fermentation makes energy available for use by microorganisms by anaerobic breakdown of carbohydrates. It can either be an acid or gas. When positive turns red to yellow and can have gas present which form bubbles.
H2S production: H2S is a toxic gas produced by the decomposition of sulfur-containing amino acids cysteine and methionine or the reduction of inorganic sulfur compounds by enzymes of certain bacteria. If hydrogen sulfide is formed, it reacts with ferrous salts to form black metal sulfides that can be visualized

The sucrose fermentation was a negative for acid meaning it was a red and a negative for gas. The H2S production was a negative because remained a yellow color instead of turning black. For the motility, it was also a negative the movement only stayed in the center than spreading throughout. The indole from tryptophan was also a negative because no ring appeared on the top layer on the reagent. With finding ammonia from urea, it was also negative meaning it did not change from orange to magenta. On the starch hydrolysis, there was no presence of a lighter zone around the bacteria after the iodine was added. When it came to the casein hydrolysis the organism did not have a presence of casein hydrolysis meaning there were no presence of a clear zone around the growth. The catalase was also a negative meaning it did not react to the hydrogen peroxide which would have caused bubbles to form around the