Bacteria
...est Result 1. Control Negative 2. S. aureus Acid 3. P. vulgaris Acid, Gas 4. P. aeruginosa Negative 5. E. coli Acid, Gas A starch agar plate was used for the starch hydrolysis test. The gram-positive, gram-negative and a control - either E. coli or B. subtilis- were strake in a straight line (Figure 2) and incubated for 48 hours. Five drops of Gram¡¯s iodine were placed on each line. If the area around the line of growth is clear, starch has been hydrolyzed; if it is not clear or the entire medium turns blue, starch has not been hydrolyzed. For the Hydrogen Sulfide (H2S) production and motility test, one peptone iron agar deep tube was stab inoculated with the gram-negative unknown. The tube was stabbed up to 2/3 of the peptone iron agar deep, the cultures were incubated for 48 hours at 35¢ªC. After incubation, each culture was examined for the presence of absence of a black precipitate along the line of the stab inoculation. The IMViC test included four steps; the first step was the indole production test; 0.5 ml or 10 drops of Kovac¡¯s reagent was added to the TSB cultures. The Kovac¡¯s reagent caused a color change; deep red for a positive result; yellow or colorless for negative results. The second step was the methyl red test, a MRVP broth media tube was inoculated with the gram-negative bacteria and the tube was incubated for 48 hours at 35¢ªC. After the incubation period, 1/3 of the culture was transferred to a sterile tube. Five drops of methyl red were added to the 2/3 left in the original tube. Color change was observed thanks to the presence of the pH indicator, methyl red. The 1/3 of culture first transferred was used for the VP test, 15 drops of naphtanol and 5 drops of KOH were added to the tube. The VP test was also performed for the gram-positive bacteria. Following the VP test, the citrate utilization test was performed; the gram-negative bacterium was inoculated to a Simmons citrate agar slant using a stab-and-strake inoculation technique. The tube was incubated for 48 hours at 35¢ªC and slant was examined for any change in color from green to blue and for the presence or absence of growth. For the oxidase test, a tryptic soy agar plate was inoculated with the gram-negative bacteria using streak-line inoculation on the agar surface. An oxidase disk was added to the plate and observed for the presence of absence of a blue color. The catalase test was performed also using the streak-line inoculation, but with both gram-positive and gram-negative. Five drops of hydrogen peroxide were added to both unknowns and the plate was sealed. The culture was observed for the presence of absence of bubbles. This particular test was used to differentiate between Enterococcus (catalase negative) and Staphylococcus (catalase positive). An L-arabinose test was performed using a tube containing phenol red and a Durham tube; the tube was inoculated with the gram-positive unknown and incubated fro 48 hours at 35¢ªC. The tube was observed for color changes (from red to yellow). 4. RESULTS The isolation of the unkn...