11 Effects of Environmental Factors on Microbial Growth

A collection of flashcards covering key concepts related to the effects of environmental factors on microbial growth, including temperature, pH, oxygen requirements, osmotic pressure, and the impact of UV radiation.

Mesophiles

Microorganisms that grow best at temperatures between 20°C to ~50°C, including most pathogenic microbes.

Thermophiles

Microorganisms that thrive at temperatures between ~50°C to 80°C.

Hyperthermophiles

Microorganisms that grow at temperatures above 80°C.

Psychrophiles

Microorganisms that grow between -5°C to 20°C.

pH

Measure of acidity or basicity of a solution based on hydrogen ion concentration; pH < 7 is acidic, pH > 7 is basic.

Neutrophiles

Microbes that grow optimally at a neutral pH, typically around 7.0.

Acidophiles

Microorganisms that thrive in acidic environments (pH < 7).

Alkaliphiles

Microorganisms that prefer basic environments (pH > 7).

Obligate aerobes

Microorganisms that can only grow in the presence of oxygen.

Obligate anaerobes

Microorganisms that cannot grow in the presence of oxygen and are poisoned by it.

Facultative anaerobes

Microorganisms that can grow in both the presence and absence of oxygen but prefer oxygen.

Aerotolerant anaerobes

Microorganisms that do not require oxygen for growth but can tolerate its presence.

Microaerophiles

Microorganisms that require lower concentrations of oxygen (1%-10%) than is found in air for growth.

Osmosis

The net diffusion of water across a semipermeable membrane from an area of lower solute concentration to higher solute concentration.

Hypotonic solution

A solution with a lower solute concentration than inside the cell, leading to water influx and cell swelling.

Hypertonic solution

A solution with a higher solute concentration than inside the cell, causing water to leave the cell and resulting in plasmolysis.

Halophiles

Microorganisms that require high salt concentrations for growth.

UV radiation

A type of nonionizing radiation with a wavelength of 100-400 nm, commonly used for disinfection.

Pyrimidine dimers

Mutations caused by UV radiation where adjacent thymine or cytosine bases bond together instead of pairing across.

Reactive oxygen species (ROS)

Highly reactive molecules formed from oxygen that can damage cellular components; detoxified by enzymes like superoxide dismutase and catalase.