Aerobic: microorganisms requiring oxygen to grow

Anaerobic: microorganisms not requiring oxygen to grow

Catalase: an enzyme present in some microorganisms that converts hydrogen peroxide to water and oxygen

Cocci: bacteria that are sphere shaped

Coccobacilli: bacteria that are short rod shaped

Facultative anaerobic: microorganisms that can grow in either aerobic or anaerobic conditions

Flagella: a flexible tail-like structure on some microorganisms that assist them in moving

Gram negative: bacteria that when Gram stained appear red

Gram positive: bacteria that when Gram stained appear purple

Gram stain: a staining technique that differentiates between classes of bacteria

Indole: a substance produced by some microorganisms

Microaerobic: microorganisms that require only small amounts of oxygen to grow

Oxidase: an enzyme present in some microorganisms that allows them to combine oxygen (oxidation)

Peritrichous flagella: flagella present around the entire bacteria pH the measurement of the acidity or alkalinity of a substance

Psychrotrophic: bacteria capable of growing at temperatures below 7°C

Rods: bacteria that are rod-shaped

Serotype: bacteria within the same species that can be distinguished on the basis of their surface antigenic properties

Spores: spherical bodies produced internally by some bacteria, that are usually more resistant to heat and chemicals

Water Activity: the amount of water available for growth of a microorganism