Question | Answer |
Environmental testing is very strict, selective differention for salmonella produces what? | -hydrogen sullfite |
sythetic media | -contains pure organic and inorganic compounds in an exact chemical formula |
pure culture | a container of medium that grows only a single known species or type of microorganism |
Synthetic media: M9 medium (for E.coli) | -not expensive composition to grow (reason why we use it)
-common source of sugar
1. glucose > as carbon source
2. ammonia sulfate > N source
3. KCl, NaCl, trace metals, thiamine |
Complex media: nutrient broth | 1.Tryptone > amino acids
2.Yeast extract > vitamins,etc.
3. NaCl
-tryptone and yeast extract are not chemically defined |
physical state | -liquid media semi-solid media solid media |
general purpose media function | -for growth of a broad range organisms, such as nutrient broth |
chemical composition | -synthetic (chemically defined) and nonsynthetic (complex) |
enriched media function | extra nutrients are added, for growth of fastidous bacteria;
e.g. blood agar, chocolate blood agar, etc. |
a bacterial colony was ________ into the broth medium and _________ at 37°C for 24 hours | 1. inoculated
2. incubated |
functional types | general purpose, enriched, selective differential, anaerobic, transport, essay, enumeration |
agar is not ___________ by most ____________ | 1. degradable
2. microbes |
complex media | -contains at least one ingredient that is not chemically definable (such as animal extract)-general purpose |
Physical states of media (examples) | 1.liquid:broth does not solidify
2.semisolid:clot-like consistency; contains a low amount of solidifying agent (agar or gelatin)
3.solid-firm surface for colony formation, usually contains 1.5% of agar |
fastidious bacteria | -enriched media
-lack metabolize capabilities
-need this to grow
-defines bacteria that require growth factors and complex nutrients |
isolation | -separating one species from another |
chocolate blood agar | -enriched media made by heating blood agar to burst looks dark so called this (causing pink eye) doctors office use this often |
wound | expose a lot of nutrients to that |
broths | liquid media are water-based solutions genetically termed this ex: milk, broths, infusion |
_______ media contain a low percentage (.3-.5%) of __________, which can be used for ________ testing | 1. semi-solid
2. agar
3. motility |
A _________ organism will grow throughout in the SIM medium | motile
SIM:
Sulfide-
Indole-
Motility- |
What are the methods of culturing microorganisms? | 1.Pure culture
2.Growth media |
_____ contain a high percent (1.5%) of ___________, which enables the formation of __________ | 1.solid media
2.agar
3. discreate colonies |
agar | -a complex polysaccharide isolated from red algae, used as a solidifying agent (but not as a nutrient)
-so stable no organism can hydrolyze it |
agar provides framework to ___________ and _____________ | 1.hold moisture
2.nutrients |
agar is _____ at room temperature and _________ at boiling (100°C) solidify at (42°C) | 1.solid
2.liquifies |
_______(protein) can also be used as a solidifying agent (12%); but it can be digested by some bacteria that produce the ________ _________, which liquefies the media; used as a __________ | 1.gelatin
2.enzyme
3.gelatinase
4.diagnostic tool |
What is the agar content in a typical solid agar plate? | 1.5% |
What are the 5 I's of culturing microbes? | 1.Inoculation
2.Incubation
3.Isolation
4.Inspection
5.Identification |
What are the three properties of culture media called? | 1.Physical state
2.Chemical composition
3.functional types |
introduction of a sample into a container of media | Inoculation |
a discrete growth that comes from one cell | colony |
everything comes from original colony | pure culture of one species from cell |
What are the three basic methods to obtain isolated colonies? | 1.Quadrant Streak
2.Pour Plate
3.Spreading |
Staphylococcus | -live on skin
-manitol salt agar plate selects for staphyloccus |
differential agent of EMB plate | allows for differentiation of Lac+ and Lac- bacteria, with the help of the dyes |
selective agents of EMB plate | -use 2 dyes which bind to change groups causing cell death at low concentration
1. eosin
2. methylene blue
-select for gram negative bacteria in general |
salt(S) | -.5%
-inhibits most species that cannot tolerate salt, therefore selects for Staphylococcus species |
differential media | containing differential agents which react different with different species
-different colony colors |
Which is the most dangerous S. aureus or S. epidermidis? | S. aureus because it causes wound infections and so forth |
EMB plate, Strong acid producer is _________ (color here_______) | E. coli or metallic green sheen
-lactose positive |
Bile salts | -mixture of digestive juice
-found in digestive tract at a concentration inhibit a bacteria to grow |
selective media | -containing selective agents, which allow only one type of bacteria to grow (inhibiting others) |
Mannitol salt agar: | purpose: for isolating staphylocci from samples (2 mechanisms) |
Blood agar is also a 1.__________ bacteria exhibit different 2.__________(define) | 1. differential medium
2. hemolysin
-any biological agent that is capable of destroying RBC and causing the release of hemoglobin |
S. aureus | -most verent
-drug resistant |
________ in media can distinguish 2.____(___) from 3.______(_____) bacteria | 1.lactose
2.Lac+ (lactose fermenter)
3.Lac- (non lactose fermenter) |
selective agent and differential agent are used together or apart | -together |
Blood agar contains_________ (amino acids) and _________(with_____RBC), used for __________ bacteria such as _________ | 1.tryptic soy
2.sheep blood (sheep)
3.fastidious pathogenic bacteria
r. streptococcus |
noncoliforms | -lactose negative or (gram negative)
-don't produce acids nonpigmented because of background lavender color/light clear |
Non E.coli coliforms | -lactose positive
-dark color stain maybe dark puplish |
MacConkey agar plates | -purpose:isolating coliforms (E. coli-like)
-mechanisms: 1.Bile salt 2.Lactose |
Lac+ (coliforms)color | dark red |
Lac- (non-coliforms) color | white |
lactose | -use sugar as differential system
-disacharride
-in order to use (heat) have organism split into 2 sugars
-produce a lot of acid called colliforms |
______in plate inhibit most_______bacteria, allows________to grow | 1.Bile salts
2.gram positive
3.gram negative |
a lot of disease are transmitted from fecal matter
therefore look for with manual digestion called 1.___________ on 2._________ agar plates | 1.coliforms
2.MacConkey |
________medium contains a ________agent that absorbs oxygen or slows penetration of oxygen into medium; used for growing__________ and examples | 1.Reducing medium
2.reducing agent
3.anaerobic bacteria
-e.g. FTM (fluid thioglycollate)medium
-Brewer's anaerobic agar plates |
top most _________ bottom least _________ can only grow on bacteria bottum | -oxygenated
-anerobic |
Miscellaneous Media | 1.Carbohydrate fermentation medium
a)Acid b)gas
-use sugar not only on plates but also on broth |
What are two common fermentation products in bacteria? and define each (hint:production is detected and examples) | Acid and Gas
Acid: production is detected by color change, inoculated starts with red color/ if use sugars turns to yellow color
Gas-production is detected by gases collected in the Durham tube, gas formed by bacteria will go up and collect on top |
by looking at gas and color can determine if bacteria___________ | is capable of using sugar |
E. coli fermentation produce gas, acid, or both? | both |
Wet mounts and hanging drop mounts | -allow examination of characteristics of live cells: motility, shape, and arrangement |
fixed mounts | are made by drying and heating a film of specimen
-this smear is then stained using dyes to permit visualization of cells or cell parts |
What do dyes do? | -create contrast by imparting a color to cells or cell parts |
1 step in using staining technique | -kill bacteria
-fix cells to slide don't over fix to change original shape |
positive stains | -basic dyes (positive charge) are used, which binds to the specimen well
-surfaces of microbes are negatively charged and attract basic dyes but not acidic dyes |
negative stains | -acidic dyes (negative charge) that do not bind to the specimen, but rather around the specimen (the background) |
simple stains | -one dye is used
-positive stain type |
differential stains | -two-different colored dyes one as the primary stain and another as counterstain to distinguish cell types or parts
-positive stain types |
EMB plate | purpose: isolating coliforms
selects 4 gram negative bacteria |
What does mannitol do to S. aureus and S. epidermidis? | S. auris can ferment mannitol and the acid produced can turn medium yellow
S. epidermidis cannot ferment mannitol, colonies are white |
a single visible colony represents a pure culture or single type of bacterium isolated from a mixed culture
-process name | -isolation
a single... |
carbohydrate fermentation medium sugars | 1. sugars that can be fermented acids are produced
2. a pH indicator to show the reaction; basis for identifying certain bacteria and fungi |
special stains | emphasize certain cell parts
ex: capsule stain and flagella stain |
basic dyes | cationic, with positive charges on the chromophore (when dissovle in water ionize and form positive change)
Ex: methylene blue, crystal violet, etc. |
an isolated cell multiplies to form a discrete _________ on________ | 1. colony
2. agar |
mannitol (D) | -sugar not glucose / simple sugar
-in the medium can differentiate S. aureus from other staphylococci |
acidic dyes | -anionic with negative charges on the chromophere
Ex: India ink, nigrosine
doesn't stain cells but rather the background |
Incubation | under conditions that allow growth (O2, temp., etc.) |
differential stains examples | 1. gram stain
2. acid-fast stain
3. endospore stain |