Microbiology Chapter 6.txt

• Microbial Growth

A bacterium that grows below pH 4

An organism that does not use molecular oxygen (02) but is not affected by its presence

A complex polysaccharide derived from a marine alga and used as a solidifying agent in culture media

A graph indicating the growth of a bacterial population over time

Prokaryotic cell reproduction by division into two daughter cells

(1) Asexual reproduction beginning as a protuberance from a parent cell that grows to become a daughter cell. (2) Release of an enveloped virus through the plasma membrane of an animal cell

An enzyme that catalyzes the breakdown of hydrogen peroxide to water and oxygen

A culture medium in which the exact chemical composition is known

A visible mass of microbial cells arising from one cell or from a group of the same microbes

Microorganisms that grow and multiply in a container of culture medium

The nutrient material prepared for growth of microorganisms in a laboratory

The period of logarithmic decrease in a bacterial population; also called logarithmic decline phase

Enumeration of cells by observation through a microscope

A culture medium used for preliminary isolation that favors the growth of a particular microorganism

An organism that requires a high salt concentration for growth

An organism whose optimum growth temperature is at least 80 c; also called extreme thermophile

An organism that can grow with or without molecule oxygen (02)

An organism capable of growth in, but not requiring, 1-2% salt

The passage of a liquid or gas through a screenlike material; a 0.45 -um filter removes most bacteria

The time required for a cell or population to double in number

A toxic form of oxygen (OH*) formed in cytoplasm by ionizing radiation and aerobic respiration

An organism whose optimum growth temperature is at least 80 C; also called extreme thermophile

A culture medium in which microorganisms are implanted

The time interval in a bacterial growth curve during which there is no growth

The period of bacterial growth or logarithmic increase in cell numbers; also called exponential growth phase

The highest temperature at which a species can grow

An organism that grows between about 10 C and 50 C; a moderate-temperature-loving microbe

An organism that grows best in an environment with less molecular oxygen (O2) than is normally found in air

A statistical determination of the number of coliforms per 100 ml of water or 100 g of food

Nutrient broth containing agar

A complex medium made of beef extract and peptone

An organism that requires molecular oxygen (O2) to live

An organism that does not use molecular oxygen (O2) and is killed in the presence of O2

An organism that requires high osmotic pressures such as high concentrations of NaCl

The temperature at which a species grows best

An essential organic compound that an organism is unable to synthesize

An enzyme that breaks down hydrogen peroxide

An oxygen anion consisting of two atoms of oxygen (02 2-)

Loss of water from a cell in a hypertonic enviroment

A method of determining the number of bacteria in a sample by counting the number of colony-forming units on a solid culture medium

A method ofinoculating a solid nutrient medium by mixing bacteria in the melted medium and pouring the medium into a Petri dish to solidify

An organism that grows best at about 15 C and does not grow above 20 C; a cold-loving microbe

The process of diluting a sample several times

Highly reactive molecular oxygen (O2 -)

A plate count method in which inoculum is spread over the surface of a solid culture medium

The period in a bacterial growth curve when the number of cells dividing equals the number dying

Free of microorganisms

A method of isolating a culture by spreading microorganisms over the surface of a solid culture medium

An enzyme that destroys superoxide free radicals

A toxic form of oxygen (O2 -) formed during aerobic respiration

The living together of two different organisms or populations

An organism whose optimum growth temperature is between 50 C and 60 C; a heat-loving microbe

A chemical element required in small amounts for growth

The cloudiness of a suspension