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an organism that thrives in a relatively acid environment


Microorganism requiring alkaline pH environments.


An organism with a growth temperature optimum of 15 degrees Celsius or lower and a maximum growth temperature below 20 degrees Celsius.


A ____ is a mesophile that is able to grow at cold temperatures.


..., bacteria that prefer moderate temperature and develope best at temperatures between 25C and 40C


..., an organism that has adapted to living in very high temperatures (heat), such as bacteria or algae


A microorganism that has a growth temperature of 80 degrees Celsius or greater.

Organic growth factor

..., Essential organic compounds which the organism is unable to synthesize and must be obtained from their environment. e.g., humans and their vitamins


..., an organism especially a bacterium that requires air or free oxygen for life


..., an organism (especially a bacterium) that does not require air or free oxygen to live

Facultative anaerobe

..., organism that can survive with or without oxygen


..., Microbes that grow better at high CO2 concentrations


..., an organism that does not grow at normal atmospheric concentrations of oxygen but requires a small amount in metabolism.

Superoxide dismutase

..., an enzyme that catalyzes the conversion of superoxide into hydrogen peroxide and oxygen


..., enzyme found in most plant and animal cells that functions as an oxidative catalyst

Selective growth media

..., Contains chemicals and/or dyes to prevent certain bacteria from growing. Can also be used to select for antibiotic resistant organisms.

Differential growth media

..., Contains various substrates and pH indicators to indicate presence/absence of certain chemical reactions; organisms not prevented from growing. Commonly used to identify organisms that break down a particular substrate.

Enrichement growth media


Complex media

..., culture media that is made up of nutrients. When liquid it is called a nutrient broth. When contains agar called nutrient agar

Defined media

..., Culture media whose exact chemical composition is known.


microorganism that grows best at neutral pH range (5.5-8.0)

Microbial growth

increase in number of cells, not cell size

Bacteria pH

pH must be between 6.5-7.5, unless the bacteria makes food--then it likes the pH lower than 6.0

Fungi pH

5 - 6 acidic


Obtain almost all nutrients in solutions from surrounding water so they grow best in an environment largely made of water.

Obligated halophiles

Require high levels of salt, members of the Domain Achaea

Facultative halophiles

Tolerate a high salt concentration, also called osmotolerant. (Ex.Staphylococcus grows in 7.5% NaCI)

Water: chemical requirement

All metabolic active cells require adequate amounts of moisture.

Carbon: chemical requirements

Structural backbone of all organic cell components

Nitrogen: chemical requirements

Needed for synthesis of protein and nucleic acids

Sulfur:chemical requirements

Needed to synthesize protein and some vitamins

Phosphorus: chemical requirements

Needed to make nucleic acids,phospholipids and ATP

Trace elements: chemical requirements

Mineral elements required by microbes in very small amounts. Usually function as cofactors.

Organic growth factor: chemical requirements

Essential organic compounds that an organism is unable to synthesize. Some bacterial require many,some require few, some none at all.


Steals electrons from other molecules creating free radicals.

Enzyme superoxide dismutase

Degrades (SOD) to hydrogen peroxide and oxygen

Hydrogen peroxide

Oxides cellular components

Enzyme catalase

Degrades this to water and oxygen, peroxides also degrades this to water also.


Any nutrient material prepared for the growth of microbes in the lab

Medium requirements

Must meet physical and chemical needs of the microorganism

Medium requirement

Must be sterile before being incoculated

Medium requirement

Pure culture versus mixed culture

Cultural solid media

Contains about 1.5% agar; most bacteria absorb nutrients from medium; colonies grow faster at edges

Culture liquid media

Grow of microbes make broth turgid; some species will not grow in certain areas of the broth due to oxygen requirements

Selective media

Contains special additives to encourage growth of desired microbes while inhibiting the growth of others.

Differential media

Contains agents that make it easier to distinguish colonies of the desired microbe.

Enrichment media

Allows for growth of organism present at low numbers, usually precedes growth on selective media

General media: complex

Contains variety of ingredients including meat juices,digestive proteins, beef and yeast extract; exact composition and amounts of each are unknown and variable; used to grow a variety of microbes

General media: Defined

Mixture of pure chemicals, exact chemical compositions is known; used to study the study the nutritional requirements of bacteria

Binary fission

Type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells

Bacterial growth curve: Lag Phase

No increase in cell numbers but cells are very metabolically active, is a period of adaptation

Bacterial growth curve: Log/exponential phase

Dramatic increase in cell number,cell divide at constant rate so generation time is measured here,bacteria are most susceptible to chemicals,ends when nutrients are depleted and wastes accumulates

Bacterial growth curve: Stationary phase

Rate or reproduction equals rate of death

Bacterial growth curve: Death/Decline phase

Death rate exceeds the rate of reproduction, cells may undergo involution,can avoid death by transferring cells to fresh culture medium

Stock cultures

Pure cultures stored,serve as a source for working cultures,never used in lab studies

Preservation of bacterial cultures

Frequent culture transfer:keeps cells active, refrigerated for short-term storage, deep freezing at -70C in glycerol, cells are frozen, dehydrated,sealed under vacuum


Cells are frozen,dehydrated,sealed under vacuum


an organism that can grow in, or favors environments that have very high salt concentrations

Generation time

time required for cell to grow and divide, population doubles


15-20 degrees celsus


25-40 degrees celsus


80 or higher degrees celsus

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