Factors That Influence Growth of Bacteria

Flashcards on the factors influencing the growth of bacteria, including nutritional requirements, oxygen, temperature, pH, and water activity.

Nutrients

Major elements, trace elements, energy and carbon sources, growth factors required for bacterial growth.

Major elements

Elements like C, H, O, N, S, and P, crucial for functional and structural roles in bacterial cells.

Trace elements

Metal ions required in small amounts, acting as cofactors for essential enzymatic reactions.

Growth factors

Organic compounds required in small amounts that organisms cannot synthesize, necessary for specific roles in biosynthesis (e.g., purines, pyrimidines, amino acids, vitamins)

Obligate aerobes

Bacteria that require oxygen for growth; use O2 as a final electron acceptor.

Obligate anaerobes

Bacteria that do not need or use oxygen; oxygen is toxic to them, and they use fermentation or anaerobic respiration.

Facultative anaerobes

Bacteria that can switch between aerobic and anaerobic metabolism, using fermentation or anaerobic respiration in the absence of oxygen and aerobic respiration when oxygen is present.

Aerotolerant

Bacteria that live by fermentation alone, whether or not oxygen is present.

Microaerophiles

Bacteria that grow best in low concentrations of oxygen (e.g., 5% O2).

Superoxide dismutase

Enzyme that eliminates superoxide radicals by converting them to hydrogen peroxide, protecting cells from oxygen toxicity.

Catalase

Enzyme that converts hydrogen peroxide to molecular oxygen and water, protecting cells from oxidative damage.

Peroxidase

Enzyme that converts hydrogen peroxide to water, especially in organisms lacking catalase.

Psychrophiles

Cold-loving microorganisms that can grow at 0°C with an optimum temperature between 10-15°C.

Psychrotrophs

Microorganisms that can grow at 0°C but have an optimum temperature in the mesophilic range (near room temperature).

Mesophiles

Moderate temperature-loving microorganisms.

Thermophiles

Heat-loving microorganisms.

Extreme thermophiles (Hyperthermophiles)

Microorganisms that thrive in very high temperatures.

Acidophiles

Microorganisms that grow well in acidic conditions (below neutral pH).

Neutrophiles

Microorganisms that grow best at neutral pH.

Alkaliphiles

Microorganisms that grow best under alkaline conditions.

Halophiles

Organisms that require salt for growth.

Xerophiles

Organisms that live in dry environments.

Osmophiles

Organisms that live in environments high in sugar.

Isotonic environment

Environment where there is no net flow of water into or out of the cell.

Hypertonic environment

Environment with a higher solute concentration outside the cell, causing water to move out and dehydrate the cell.

Hypotonic environment

Environment where the solute concentration is higher inside the cell, causing water to flow in and potentially burst the cell.

Selective medium

Medium that prevents the growth of certain bacteria while promoting the growth of desired species.

Differential medium

Medium that allows differentiation between different types of bacteria based on observable growth patterns or changes.

Enrichment medium

Medium containing blood or tissue extracts to support the growth of fastidious (