Microbial Growth and Environmental Factors

These flashcards cover key vocabulary relevant to microbial growth, environmental factors affecting microbes, and reproduction methods in microorganisms.

chemical equilibrium

A state in which the concentrations of reactants and products remain constant over time.

pH

A measure of acidity or alkalinity of a solution, affecting enzyme function and microbial growth.

mesophiles

Organisms that grow best at moderate temperatures, typically around 37 degrees Celsius, which include many human pathogens.

psychrophiles

Bacteria that thrive at extremely low temperatures, often found in cold environments.

thermophiles

Microorganisms that prefer and thrive at high temperatures.

hyperthermophiles

Microorganisms that grow at extremely high temperatures, such as those found in geothermal vents.

endospores

Dormant, tough structures formed by some bacteria to survive extreme conditions; highly resistant to damage.

quorum sensing

The regulatory mechanism by which bacteria communicate and coordinate behavior based on their population density.

biofilm

A complex aggregation of microorganisms growing on a surface, often encased in a protective extracellular matrix.

oxygen tolerance

The ability of organisms to survive and grow in the presence or absence of oxygen.

aerobes

Organisms that require oxygen for growth.

anaerobes

Microorganisms that do not require oxygen for growth and can even be harmed by it.

facultative anaerobes

Organisms that can grow with or without oxygen, using aerobic respiration when oxygen is present and anaerobic processes when it is absent.

obligate anaerobes

Microorganisms that cannot tolerate oxygen and must live in an oxygen-free environment.

chemoautotrophs

Organisms that obtain energy by oxidizing inorganic substances and use carbon dioxide as their carbon source.

photoautotrophs

Organisms that use sunlight to synthesize their own food from carbon dioxide.

saprophytes

Organisms that feed on dead or decaying organic matter.

osmotic pressure

The pressure required to prevent the flow of water across a semipermeable membrane, important in maintaining cell turgidity.

water activity

A measure of the availability of water for microbial growth; lower values limit growth.

chemostat

A device that maintains a microbial culture in a state of continuous growth by adding fresh medium and expelling waste.

lag phase

The period of time in which bacterial cells adapt to a new environment before beginning to divide.

log phase

The phase of rapid cell division and growth in a bacterial culture, characterized by exponential increase in numbers.

stationary phase

The phase in which growth rate slows and stabilizes due to depleted resources or accumulation of waste products.

differential staining

A technique that utilizes specific stains to distinguish between different types of cells or structures.

crossing over

The exchange of genetic material between homologous chromosomes during meiosis, contributing to genetic diversity.