Chapter 6 - Micro

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adapted to high salt concentrations, which are required for growth

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extreme halophile

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the general term used for organisms capable of growth at 0 degree C

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psychrophile

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capable of growth at high temperatures; optimum of 50-60 degree C

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thermophile

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used in media to neutralize acids

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buffer

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a phenomenon that occurs when bacteria are placed in high salt concentrations

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plasmolysis

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term used in text for organisms that grow well at refrigerator temperatures; optimum growth is @ temperatures of 20-30 degree C

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psychotroph

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microbes that grow better @ high CO2 concentrations

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capnophile

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members of the archaea w/ an optimum growth temperature of 80 degrees C or higher

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hyperthermophile

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considered a synonym for psychotroph by some microbiologists

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facultative pscyhoPHILE

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an enzyme acting upon hydrogen peroxide

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catalase

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Rhizobium bacteria do this in symbiosis w/ leguminous plants

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nitrogen fixation

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requires atmospheric oxygen to grow

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obligate aerobe

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does not use oxygen, but grows readily in its presence

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microaerophile

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does not use oxygen andusually finds it toxic

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obligate anaerobe

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important source of energy, carbon, nitrogen and sulfur requiremetns in complex media

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peptones

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breaks down hydrogen peroxide w/o generation of oxygen

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peroxidase

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formed in cytoplasm by ionizing radiation

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hydroxyl radical

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an enzyme that converts hydrogen peroxide into oxygen and water

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catalase

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the toxic form of oxygen neutralized by superoxide dismutase

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superoxide free radicals

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a component added to some culture media that makes the Petri plate into a self-contained anaerobic chamber

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oxyrase

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isolation method for getting pure cultures; uses an inoculating loop to trace a pattern of inoculum on a solid medium

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streak plate

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a device for maintaining bacteria in a logarithmic growth phase

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chemostat

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used to increase the numbers of a small minority of microorganisms in a mixed culture to arrive at a detectable level of microorganisms

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enrichment culture

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preservation method that uses quick-freezing and a high vacuum

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lyophilization

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accumulations of microbes large enough to see w/o a microscope

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colonies

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microbes added to initiate growth

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inoculum

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new cell #'s balanced by death of cells

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stationary phase

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no cell division, but intense metabolic activity

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lag phase

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a logarithmic plot of the population prouduces an ascending straight line

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log phse

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used to grow obligate an aerobes

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reducing media

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designed to suppress the growth of unwanted bacteria and to encourage growth of desired microbes

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selective media

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generaly contain ingredients such as sodium thioglycolate that chemically combine w/ dissolved oxygen

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reducing media (?)

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nutrients are digets or extracts; exact chemical composition varies slightly from batch to batch

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complex media

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Agar is a ____ derived from a marine alga.

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polysaccharide (solidifying agent)

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A few bacteria nd the photosynthesizing ______ are able to use gaseous nitrogen directly from the atmosphere.

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cyanobacteria

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_______ are the most common microbes; their optimum temperatures are 25-40 degrees C.

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mesophiles

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osmotic effects are roughly related to the _____ of molecules in a given voluem of solution.

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number

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a complex medium in liquid form is called a nutrient ______.

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broth

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for preservation by _______, a pure culture of microbes is plased in a suspending liquid and quick frozen at -50 - -95 degrees C.

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deep freezing

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bacteria usually reproduce by _____.

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binary fission

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turbidity is recorded in a spectrophotometer as _______.

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absorbance (optical density)

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the growth of filamentous organisms such as fungi is often best recorded by means of _______.

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dry weight

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____ anerobes grow more efficiently aerobically than they do anaerobically.

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facultative anaerobes

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____ halophiles do not require high salt concentrations, but they are able to grow at salt concentrations that may inhibit the growth of many other bacteria.

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facultative

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examples of buffers are ______ salts, peptones and ____ found in complex media are also buffers.

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phosphate salts, amino acids

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any nutrient material prepared for the growth of bacteria in a lab is called a ______.

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culture medium

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agar melts at the boiling point of water but remains liquid until the temperature drops to about ______.

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40 degrees C

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dilutions of a bacterial mixture are poured into a petri dish and mixed w/ melted agar. This plate counting method is called the _______.

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pour plate method

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partially digested protein products used in complex media are called ______.

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peptones

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in order to grow obligate intracellular parasites such as rickettsias and chlamydias, it is usually necessary to provide _____.

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living host cells

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the general term for tests that estimate microbial growth by the time required for them to deplete oxygen in the medium is _____ tests.

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reduction

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the _______ growth temperature is that at which the organism grows best.

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optimum

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when a single colony arises from a clump of bacteria, it is recorded as a ______.

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cfu