Microbiology Tests

Enzyme Detection Tests

• Oxidase test detects cytochrome c oxidase enzyme using tetra-methyl-p-phenylenediamine dihydrochloride, with a positive result indicated by a blue color.
• Catalase test identifies bacteria that produce the catalase enzyme, using hydrogen peroxide, with a positive result indicated by a bubble reaction.

Metabolic Activity Tests

• Nitrate reduction test determines a bacterium's ability to reduce nitrate to nitrite or further compounds, using sulfanilic acid and naphthylamine as reagents, with a positive result indicated by a red color.
• Ferment glucose test evaluates an organism's ability to ferment glucose and produce gaseous products, using phenol red as a pH indicator, with a positive result indicated by a yellow or orange color.
• Ferment lactose test determines a bacterium's ability to ferment lactose as a carbon source, using phenol red as a pH indicator, with a positive result indicated by a yellow or orange color.
• Fermentation mannitol test evaluates a bacterium's ability to ferment mannitol as a carbon source, using phenol red as a pH indicator, with a positive result indicated by a yellow or orange color.
• Methyl red (MR) test/Voges-Proskauer (VP) test detects mixed acid fermentation and the production of butanediol, using methyl red dye, with a positive result indicated by a red color.

Amino Acid Metabolism Tests

• Phenylalanine agar test (Simmons test) determines a bacterium's ability to oxidatively deaminate l-phenylalanine to phenylpyruvic acid, using ferric chloride and hydrochloric acid, with a positive result indicated by a green color.

Carbon Source Utilization Tests

• Simmons citrate test determines a bacterium's ability to use citrate as its sole carbon source, with a positive result indicated by a blue color.
• Kligler iron test detects the production of acid from fermented carbohydrates and gas production, using phenol, with a positive result indicated by a yellow color, black sulfur reduction, and cracks or lifting indicating gas production.

Lipase and Protein Hydrolysis Tests

• Spirit blue lipase test detects lipase enzyme production, using olive oil and spirit blue dye, with a positive result indicated by a yellow clearing of the zone.
• Starch hydrolysis test determines a bacterium's ability to hydrolyze starch using enzymes, using iodine, with a positive result indicated by a red color with iodine overgrowth of the zone.
• Casein hydrolysis test determines a bacterium's ability to synthesize caseinase enzyme, with a positive result indicated by clearing of the zone.
• Gel deep test detects the ability to produce gelatinase, with a positive result indicated by a liquid medium.

Urea Hydrolysis Test

• Urease test determines a bacterium's ability to hydrolyze urea using the urease enzyme, using phenol red, with a positive result indicated by a pink color.

Isolation and Differentiation Tests

• MacConkey agar test isolates gram-negative bacteria and differentiates them based on lactose fermentation, using crystal violet, bile salts, lactose, and neutral red.