Bacterial Growth Factors and Hydrolysis Tests

Flashcards covering bacterial growth factors such as oxygen and temperature requirements, as well as biochemical enzyme tests including starch, DNA, lipid, and casein hydrolysis tests.

Fluid Thioglycollate Medium (FTM)

A medium used to test the oxygen requirements of bacteria, also serves as a differential medium as bacteria grow in different parts where oxygen concentration best suits their metabolic needs.

Obligate Aerobe

A microorganism that requires oxygen for growth and will be found at the top of FTM where O2 concentration is high.

Obligate Anaerobe

A microorganism that cannot grow in the presence of oxygen and will be found at the bottom of FTM, below the resazurin dye, where there is little to no O2.

Facultative Anaerobe

A microorganism that can grow with or without oxygen, capable of aerobic and anaerobic respiration or fermentation, and will grow throughout the FTM test tube.

Microaerophile

A microorganism that requires oxygen but only at lower than atmospheric concentrations, growing in the middle or upper-middle part of the FTM medium.

Aerotolerant Anaerobe

A microorganism that does not use oxygen but can detoxify it and is not affected by its presence, thus being evenly spread along the FTM test tube.

Reactive Oxygen Species (ROS)

Toxic products of oxygen metabolism, including superoxide ion (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (OH).

Superoxide Dismutase

An enzyme that detoxifies superoxide ions (O2-).

Catalase

An enzyme that detoxifies hydrogen peroxide (H2O2).

Cardinal Temperatures

The minimum, optimum, and maximum temperatures at which a microorganism can grow.

Psychrophile

A microorganism that grows only below 15°C.

Psychrotroph

A microorganism adapted to grow between 0°C and 30°C.

Mesophile

A microorganism adapted to grow between 15°C and 45°C; most human pathogens fall into this category.

Thermophile

A microorganism adapted to grow above 45°C.

Extreme Thermophile

A microorganism that grows best above 80°C.

Chromobacteria

Bacteria known for producing pigments, with production often depending on environmental factors like pH, temperature, and light.

Starch Hydrolysis Test

A test identifying the presence of α-amylase and oligo-1,6-glucosidase, enzymes that hydrolyze starch, indicated by a clear zone around growth after adding iodine.

Iodine (Starch Hydrolysis)

An indicator used in the starch hydrolysis test; it turns brown or blue-black in the presence of residual starch, while a clear zone indicates starch digestion.

DNA Hydrolysis Test

A test identifying organisms that produce deoxyribonuclease (DNase), with methyl green dye as an indicator.

Deoxyribonuclease (DNase)

An enzyme that hydrolyzes DNA, causing the methyl green dye-DNA complex to break down and the medium to clear.

Methyl Green Dye (DNA Hydrolysis)

An indicator used in the DNA hydrolysis test; forms a blue-green complex with DNA, and a clearing of the medium indicates DNA hydrolysis.

Lipid Hydrolysis Test

A test identifying the presence of lipases which hydrolyze lipids (triglycerides like tributyrin oil), indicated by a clearing of the cloudiness in the agar.

Tributyrin Oil

The differential agent (a triglyceride) used in the lipid hydrolysis test; its hydrolysis by lipase results in a clear zone.

Lipase

An enzyme that hydrolyzes lipids or triglycerides, allowing bacteria to transport fatty acids into cells for further metabolism via β-oxidation.

Casein Hydrolysis Test

A test identifying the presence of casease, an enzyme that hydrolyzes casein (the primary protein in milk), indicated by a clearing of the white color in milk agar.

Casein

The primary protein in milk, used as the differential agent in the casein hydrolysis test; its hydrolysis by casease results in a clear zone.

Casease

An enzyme that hydrolyzes the milk protein casein, leading to a visible clearing zone around bacterial growth on milk agar.