Oxygen Requirements and Nitrate Test

These flashcards cover key terms and concepts related to oxygen requirements and nitrate testing methods in bacteria, highlighting important definitions and processes.

Obligate Aerobes

Bacteria that require oxygen for aerobic respiration.

Facultative Anaerobes

Bacteria that can use oxygen when available but can also perform anaerobic respiration or fermentation.

Obligate Anaerobes

Bacteria that cannot survive in the presence of oxygen.

Microaerophiles

Bacteria that require lower than atmospheric levels of oxygen.

Aerotolerant Anaerobes

Bacteria that do not use oxygen but are not harmed by it.

Oxygen Gradient

A concentration range of oxygen from high at the top to low at the bottom of a medium.

Fluid Thioglycollate Broth

A medium used to test bacterial oxygen tolerance.

Resazurin

An oxygen indicator that turns red when oxidized and colorless when reduced.

Catalase Test

A test that determines if bacteria produce catalase to detoxify hydrogen peroxide.

Superoxide Dismutase

An enzyme that converts superoxide radicals to hydrogen peroxide.

Oxidase Test

A test used to determine the presence of cytochrome c oxidase in bacteria.

Tetramethyl-p-phenylenediamine (TMPD)

A chromogenic reducing agent used in the oxidase test.

Anaerobic Respiration

The process of reducing an inorganic molecule other than oxygen.

Nitrate Reductase

An enzyme that reduces nitrate to nitrite.

Denitrification

The process of converting nitrate to nitrogen gas.

Assimilatory Nitrate Reduction

The reduction of nitrate to ammonium for amino acid synthesis.

Nitrate Broth

A medium containing potassium nitrate used for nitrate reduction tests.

Durham Tube

A tube used to detect gas production in fermentation and reduction tests.

Nitrite

The intermediate product when nitrate is reduced by nitrate reductase.

Nitrogen Gas

The final product of denitrification when nitrate is fully reduced.

Nitrate Reduction Test

A test to determine if bacteria can reduce nitrate.

Zinc Powder

A reducing agent used to test for unreacted nitrate in the nitrate reduction test.

Ammonium (NH4+)

The end product when nitrate is reduced to ammonium.

Sodium Thioglycolate

A reducing agent in Fluid Thioglycollate Broth that helps create an oxygen gradient.

Catalase Positive

Organisms that can produce catalase to break down hydrogen peroxide.

Oxidative Phosphorylation

A metabolic pathway that uses oxygen as the terminal electron acceptor.

Facultative Anaerobic Respiration

The ability to switch between aerobic and anaerobic respiration.

Superoxide Radical (O2-)

A toxic form of oxygen produced during aerobic respiration.

Hydrogen Peroxide (H2O2)

A less toxic byproduct of superoxide dismutation.

Oxidized TMPD

The form of TMPD that turns purple when cytochrome c oxidase is present.

Gas Pak Jar

A device used for culturing obligate anaerobes by creating an anaerobic environment.

Candle Jar

A device used for culturing microaerophiles by creating a microaerobic environment.

Electron Transport Chain (ETC)

The series of proteins in the cellular membrane that transfer electrons to generate ATP.

Reactive Oxygen Species (ROS)

Toxic oxygen-containing molecules produced during aerobic respiration.

Catalase

An enzyme that catalyzes the conversion of hydrogen peroxide into water and oxygen.

Colorless TMPD

The reduced form of TMPD that indicates a negative oxidase test.

Reduced TMPD

The form of TMPD that is colorless before oxidation and turns purple when oxidized.