chapter five - bacterial growth and nutrition

Pure culture,A culture containing a single species

Liquid media,Culture media that allows bacteria to move freely

Solid media,Culture media useful for separating mixtures of different organisms

Agar,Added to solid media to make a firm surface where bacterial cells form colonies

Colony,A group of bacterial cells that forms on solid media

Isolation streaking,Allows separation of colonies into pure cultures

General purpose medium,Nutrient agar that grows most non-fastidious bacteria

Defined medium,Medium in which the composition of inorganic or organic components is known precisely and often contains growth factors to help specific bacteria grow

Complex medium,Medium whose exact composition is unknown and often contains animal byproducts such as blood milk yeast extract or beef extract

Selective media,Media in which some bacterial species are prevented from growing while others are favored

Differential media,Media in which species grow equally well but metabolize compounds differently and are often distinguished by a color difference

MacConkey medium,Selective and differential medium that uses bile salts and crystal violet to select for Gram-negative enteric bacteria and lactose to differentiate fermentation

Mannitol Salt Agar,Selective for Staph and differential between Staph species

Thayer Martin,Selective for Neisseria

Lowenstein-Jensen,Selective for Mycobacterium tuberculosis

Exponential growth,Population size doubles at a fixed rate

Generation time,Constant interval at which bacteria divide when resources are plentiful

Bacterial growth phases,Lag exponential stationary and death

Essential nutrients,Compounds a microbe cannot make itself and must gather from its environment to grow and divide

CHONPS,Carbon hydrogen oxygen nitrogen phosphorus and sulfur

Autotrophs,Make their own carbon compounds starting with CO2

Heterotrophs,Obtain carbon compounds from other organisms

Phototrophs,Use light as an energy source

Chemotrophs,Use potential energy stored in chemical compounds as an energy source

Lithotrophs,Use inorganic chemical compounds as an energy source

Organotrophs,Use organic chemical compounds as an energy source

Nitrogen,Nutrient needed by cells to make proteins and nucleic acids

Nitrogen cycle,Converts unusable nitrogen into usable forms

Nitrogen fixation bacteria,Convert N2 into ammonium ions creating a usable form of nitrogen in soil

Nitrifying bacteria,Convert NH3 into nitrate or nitrite creating a form accessible to plants

Denitrifying bacteria,Convert nitrate or nitrite into gaseous N2 and are used in wastewater management

Extremophiles,Bacteria archaea and some eukaryotic microbes that can grow in extreme environments

Thermophiles,Microorganisms that can grow at high temperatures up to 158°F

Hyperthermophiles,Microorganisms that grow at temperatures as high as 250°F under extreme pressure

Mesophiles,Microorganisms with a growth range between 68-104°F; most pathogenic microorganisms are mesophilic

Psychrophiles,Microorganisms that grow at temperatures as low as 14°F

Barophiles,Microorganisms adapted to grow at very high pressures such as locations deep within the ocean

Osmolarity,A measure of the number of solute molecules in a solution

Halophiles,Some species of archaea that require high concentrations of salt and create a pink or red color in hypersaline environments

Neutralophiles,Microorganisms that grow between pH 5-8; includes most human pathogens

Acidophiles,Microorganisms that live in acidic environments

Alkaliphiles,Microorganisms that grow best at pH 9-11

Obligate aerobes,Require oxygen for energy metabolism and survive only in environments with oxygen

Obligate anaerobes,Do not require oxygen for energy metabolism and survive only in environments without oxygen

Microaerophiles,Aerobic microorganisms that survive in environments with lower oxygen concentrations

Aerotolerant anaerobes,Anaerobic microorganisms that prefer anaerobic conditions but can survive oxygen

Facultative anaerobes,Microorganisms that are aerobic and anaerobic and can survive with or without oxygen

Biofilm,A mass of bacteria that stick to and multiply on a solid surface and can include one or multiple collaborating species

Endospores,Destruction-resistant structures produced by certain Gram-positive bacteria that are dormant and require no nutrition or energy

Vegetative cells,Live bacterial cells that are not in the spore state

Bacillus,Genus that can produce endospores such as Bacillus anthracis

Clostridium,Genus that can produce endospores such as Clostridium botulinum and Clostridium tetani