Bio 206 Lab Exam 1 - TERMS

ubiquitous in nature

found everywhere

saprophytes

perform important role of decomposition in the ecosystem

pathogens

cause damage to the host

mutualism

• (both host and microbe benefit)

commensals

• (microbe benefits but no effect on host)

reservoir

• area where a microbe with the potential to cause infection resides

blood agar

• To differentiate bacteria based on their hemolytic characteristics

• 
  

3 major types of hemolysis

β – hemolysis

α – hemolysis:

γ – hemolysis:

β – hemolysis

complete destruction; results in clearing of the medium

• very shiny

α – hemolysis:

• partial destruction; results in greenish discoloration of the medium

• somewhat shiny

γ – hemolysis

• no hemolysis

• no shine

colony

visible mass of cells

growth is influenced by nutrient availability, temperature, incubation time

filiform

• dense and opaque with a smooth edge

friable

crusty

spreading edge

• produced by motile organisms

growth patterns

• pellicle

• sediment

• uniform fine turbidity

• flocculent

pellicle

growth floats on top of the medium

sediment

growth sinks to the bottom

uniform fine turbidity

cloudy

flocculent

clumped growth

germicides

• Refers to substances or systems, both chemical and physical, that prevent the spread of pathogens

categories of germicides

• decontamination

• disinfect

• sterilization

decontamination

• lowest level of control

• reduction of pathogenic microorganisms to a level at which items are safe to handle without protective attire”

• soaps or detergents

disinfection

• next level of control

• low, medium, or high = based on effectiveness

• chemical sterilants

• antiseptics

chemical sterilants

high - level disinfectants that have the ability to kill all vegetative cell and some spores

antiseptics

• Disinfectants designed to reduce or eliminate pathogens on or in living tissue 

sterilization

• Highest level of pathogen control

• autoclave = device used for ______

autoclave

• Sterilizing temperature is set between 121°C and 127°C

• Must reach optimum temperature for a least 15 minutes

• Time varies according to the size and consistency of the material

• Color-coded autoclave tape

aseptic transfer

• Transfer of living microbes from one place to another without contamination of:

  • The culture

  • The sterile medium

  • Or the surroundings

• to prevent you have to inoculate instruments

preventing contamination of instruments process

• Inoculating instruments must be sterilized prior to use

  • Wire loops are sterilized immediately before use in an incinerator.  

  • Cool loop in agar before transfer

  • Mouths of tubes containing culture or media are also incinerated at the time of transfer

  • Instruments that can not be incinerated are sterilized inside wrappers or containers by autoclaving prior to use

culture

• A medium that contains living microbes

pure culture

• one that contains a single species

mixed culture

• one that contains multiple species

• all culture are assumed to be ____ prior to obtaining isolation

media

Microbial cultures are grown and maintained on or in solid and liquid substances

types of media

• broths

• agar slants

• plated media

broths

•  used to grow microbes when fresh cultures or large number of cells are required

agar slants

• generally used to grow stock cultures that can be refrigerated after incubation and maintained for several weeks

plated media

•  typically used for obtaining isolation of species, differential testing, and quantifying bacterial densities

methods of isolation

• spread plate

• streak plate

• pour plate

quadrant streak method

• A bacterial sample is streaked over the surface of a plated agar medium.

• During streaking, the cell density decreases,

micropipettes units

uL or mL (must convert),

ex: 100-1000 uL in a 1000 micropipette

spread plate

• A method of isolation in which a diluted microbial sample is deposited on an agar plate and spread uniformly across the surface

• colony forming units/CFUs

• If properly diluted, cells (colony forming units/CFUs) will be deposited far enough apart on the agar surface to grow into individual colonies

• After incubation, a portion of an isolated colony can be transferred to a sterile medium to begin a pure culture

• Also can be used to quantify cell density of a broth culture

antimicrobials

• term used to describe agents that are used to kill or inhibit the growth of microorganisms like bacteria, fungi, viruses, or protozoa

antibiotics

• antimicrobial agents that specifically target bacterial cells to kill or inhibit growth

• treat infections in humans and animals

bactericidal

kills the bacteria

bacteriostatic

inhibits growth but does not kill

kirby-bauer test (disk diffusion test)

• measures effectiveness of antimicrobials against pathogenix microorganisms

• A plate is inoculated to form a “lawn” of bacteria

• Disks coated with antimicrobials are placed on a plate

• Plates are incubated to allow growth of the bacteria and time for the agent to diffuse

• If the organism is susceptible, a clear zone, where growth is inhibited, will appear around the disk

  • Size of the “zone of inhibition” depends upon the sensitivity of the bacteria to the specific microbial agent

hemaggultination

• term applied to any agglutination test in which clumping of red blood cells indicates a positive reaction

universal donor

type O- blood

universal recipient

type AB+ blood

bacteriophages

viruses that infect bacteria

bright-field microscopy

produces an image made from light transmitted through a specimen

formula for total magnification

total magnification = magnification of ocular lens x magnification of objective lens

types of microscopy

• dark-field microscopy

• phase contrast microscopy

• fluorescence microscopy

fluorescene

• high energy light outside the visible spectrum strikes the sample

• absorb that light and emit lower energy

bacterial morphology

allow to see cellular morphology which include

• size

• shape

• arrangement

• other structures or differentiating features

cocci

cell shape for sphere

bacilli

cell shape for rods

spirilla

cell shape for spirals

vibrios

slightly curved rods

coccobacilli

ovoid shape between a cocci and bacilli (oval)

spirochetes

flexible spirals

pleomorphism

a single species that exhibits a variety of cell shapes within a given sample

diplococci

one plane of division

streptococci

one plane of division, but cells do not separate and instead form a long chain

tetrad

two planes of division, one perpendicular to the other

sarcina

three planes of division results in cube

staphylococci

irregular division leads to a cluster of cells

bacterial stains consist of:

• solvent (water or ethanol)

• chromopre = give it color

• auxochrome = charged portion of the chromogen

simple stain

stained w a single dye that stains all cells the same color

picks up a H+ or loses a OH - and becomes positively charged

attracted to negative charges on the surface of most bacterial cells

differential stains

detect differences between organisms or between parts of the same organism

used to differentiate between gram-positive and gram-negative

gram-positive

bacteria has a very thick cell wall made of peptidoglycan BUT NO outer membrane

gram-negative

bacteria have a thin cell wall made of peptidoglycan and HAVE an outer membrane

differential stain process

• crystal violet stain both + and -

• iodine is added

• decolorization w ethanol removes crystal violet/iodine complex

• safranin used to counterstain gram negative cells

over-decolorization

leaving alcohol on too long

produces reddish-pink gram-positive cells

under-decolorization

not using alcohol long enough

produces purple gram-negative cells

negative stain

uses a dye solution in which the chromogen is acidic

• Acidic chromogen gives up a H+ and becomes negatively charged

• Negative charge on bacterial surface repels the negatively charged chromogen

• Cell remains unstained against a colored background

hemolysins

• Several species of Gram-positive cocci produce exotoxins called ______

• able to destroy RBCs and hemoglobin