Microbiology Chapter 7

Binary fission

A form of asexual reproduction in bacteria, creating two daughter cells by dividing the cell in half.

Generation time

The time required for a bacterial cell to divide and produce two daughter cells.

Log phase

The phase in bacterial growth where the population increases exponentially.

Lag phase

The phase where bacteria adjust to their environment and grow little or not at all.

Stationary phase

The phase where bacterial growth levels off due to depletion of nutrients and accumulation of waste.

E. coli

A bacterium whose growth is influenced by environmental factors such as temperature, nutrients, and antibiotics.

Optimal temperature

The temperature at which bacteria grow the fastest.

Psychrotrophs

Organisms associated with foodborne illness, capable of growing at low temperatures.

Mesophiles

Microbes that grow best at moderate temperatures, often associated with pathogens.

Extreme thermophiles

Organisms that thrive at very high temperatures, typically near thermal vents.

Acidophiles

Microbes that thrive in acidic environments, can grow in conditions such as a pickle jar with vinegar.

Halophiles

Microbes that thrive in high-salt environments.

Facultative halophile

An organism that tolerates high salt concentrations but does not require them for growth.

Obligate aerobe

Microbes that require oxygen for growth.

Facultative anaerobe

Microbes that prefer using oxygen but can survive without it.

Essential nutrients

Nutrients that a cell needs but cannot make on its own.

Growth factors

Necessary substances that a cell can't synthesize on its own.

Chemoautotroph

An organism that gets energy from breaking down nutrients and uses CO2 as its carbon source.

Defined media

Media with known chemical compositions, used for growing certain types of microbes.

Selective media

Media containing ingredients that foster the growth of certain bacteria while suppressing others.

Thioglycolate

A medium used to create anaerobic conditions for the growth of obligate anaerobes.

Coulter counter

A device that counts cells and differentiates between living and dead cells.

Viable plate count

A method for determining the number of viable cells by culturing them on agar plates.

Disinfectant

A chemical used to control microbial growth on inanimate objects.

Thermal death point

The minimum temperature needed to kill all microbes in a sample within a specified time.

Eosin-Methylene blue (EMB) media

A selective medium that produces green colonies in the presence of coliform bacteria.

Decal reduction time

The time required for a solution to decrease the viable count of a population by 90%.

Noncritical equipment

Equipment that requires low-level disinfectants for microbial removal.

Prions

Infectious agents that are resistant to standard control methods like chlorine treatment.

Differential media

Media that allows different bacteria to be identified based on their appearance.

Subculturing

The method of transferring organisms from one medium to another.

Enrichment broth

A type of culture medium that is designed to favor the growth of a particular organism.

Quantitative analysis

Methods conducted to measure the number of cells or organisms in a sample.

Biofilms

Complex communities of microbes that adhere to surfaces.

Aerotolerant anaerobe

Organisms that do not use oxygen but can tolerate its presence.

Microaerophile

Organisms that require low levels of oxygen for growth.

Turbidity measurement

A method for estimating microbial growth based on the cloudiness of a culture.

Inoculum

The material used to initiate a microbial culture.

Serial dilution

A method used to create a range of concentrations of microorganisms.

Pour plate

A method of growing bacteria by mixing them with molten agar and pouring it into a petri dish.

Colony forming unit (CFU)

A unit used to estimate the number of viable bacteria in a sample.

Antibiotics

Substances produced by bacteria that inhibit the growth of or destroy other microorganisms.

Microbial growth phases

Stages of growth for bacterial populations, including lag, log, stationary, and death phases.

Chemical agents

Substances used to control microbial growth.

Viable plate counts

Techniques used for estimating the number of cells in a culture by counting colonies.

Osmotic pressure

The force exerted by solutes in a solution; important in microbial growth.

MacConkey agar

A selective and differential medium used for isolating gram-negative bacteria.

Bioreactor

A vessel or container in which biological reactions occur, often used in fermentation.

Reducing medium

A culture medium that contains substances that reduce the concentration of oxygen.

Fastidious organisms

Microbes that have complex, specific growth requirements.

Catalase

An enzyme that breaks down hydrogen peroxide into water and oxygen, protecting cells from oxidative damage.

Metabolic activity

A measure of the biochemical processes occurring in a microbe.

Incubator

An apparatus used to maintain optimal temperature and humidity for microbial culture.

Spore formation

The process by which bacteria form spores to survive adverse conditions.

Nitrogen fixation

The conversion of atmospheric nitrogen into a usable form for microorganisms.

Molecular oxygen (O2)

A gas required by obligate aerobes for metabolic processes.

Biofilm formation

The process through which microorganisms adhere to surfaces and develop a community.

Enriching conditions

Laboratory conditions that promote the growth of specific microorganisms while inhibiting others.

Temperature sensitivity

The reaction of microbes to changes in temperature affecting their growth and survival.

Quorum sensing

A cellular communication process used by bacteria to coordinate behavior based on population density.

Microbial metabolism

The sum of the biochemical reactions occurring within a microorganism.

Pathogenic organisms

Microbes that can cause disease in a host.

Clinical sample

Specimens collected from patients for diagnostic testing.

Indigenous microbiota

Microbes that naturally live in or on the human body.

Carbon source

A compound that provides the carbon necessary for a microorganism's growth.

Infection control

Strategies used to prevent the spread of infectious diseases.

Thermoduric organism

Microbes that can survive high temperatures but do not necessarily grow well at those temperatures.

Growth-limiting nutrient

Nutrients that are in short supply and restrict microbial growth.

Oxygen requirement

The specific needs of a microbe regarding oxygen availability for growth.

Microbial isolation

The process of separating a specific microorganism from a mixed culture.

Coliform bacteria

A group of bacteria commonly used as indicators of water quality.

Direct microscopic count

A method for determining the number of cells in a sample using a microscope.

Epidemiology

The study of how diseases spread and are controlled in populations.

Microbial diversity

The variety of different microbial species in a given environment.

Centrifugation

A method used to separate particles from a solution based on density.

Inoculation loop

A tool used to transfer microorganisms into culture media.

Retention time

The amount of time a microorganism must spend in a given environment to achieve desired growth.