Microbiology Lab Exam – Flashcards

Purplish/red

Pink/fuchsia/colorless

uses more than one dye and stains different kinds of organisms different colors

differential

entire- completely round shaped indulated-wavy lobate-bigger wave erose-spikey

Lactose Fermentation

Acid=yellow Neutral=red-orange alkaline=cherry red

Lactose-a large amount Sucrose Glucose-a small amount

Acid=red Neutral=orange Alkaline=yellow

differential, differentiates between those bacteria able to make the enzyme, hemolysis and those that cannot -alpha hemolysis = green -B hemolysis = clearing -no hemolysis = yellow growth/no agar color change

Heating the smear melts the waxy coat, allowing the stain to move into the cell

Yes, they are stained initially. However, the decolorizer takes away the color on the acid-fast negative but not the acid fast positive bacteria.

very few bacteria are acid fast positive, so the test is less useful than a gram stain, which separates organisms into two large groups. -acid fast is useful when acid fast positive bacteria are suspected

diluted microbial sample is deposited on an agar plate and spread uniformly across the surface with a glass rod with a properly diluted sample, cells will be deposited far enough apart on the agar surface to grow into individual colonies

surface membrane on broth

growth on bottom of broth

don't require oxygen but are not adversely affected by it

grow in the presence of absence of oxygen

D (minimum distance at which two point can be resolved) = λ (wavelength)/ NA (numerical aperture)

a special condenser is used so only the light reflected off the specimen enters the objective -dark background

acidic stain; add bacteria to one drop of stain on slide and use another slide to spread the black ink across the slide -do not heat fix

negative = blue/purple or green positive = pink

capsule remains unstained and forms a while ring around stained cell and background -red/pink

spore producer = red with green spores inside cells nonproducer = red (safranin)

Phenylethyl alcohol agar undefined, selective media -inhibits gram negative growth -results = poor or good growth

selective (gram+), differential (mannitol) 7.5% NaCl + phenol red -poor/no growth = not staph -good growth = staph -yellow = mannitol fermentation -red = does not ferment mannitol

selective (gram-), differential (for lactose)media -ability to ferment lactose -poor/no growth = gram positive -good growth = gram negative -pink/red = lactose fermentation, coliform -colorless = no reaction/fermentation

selective (gram -), differential (lactose, sucrose) dyes inhibit growth of gram positive organisms and react with lactose fermenters -poor/no growth = gram positive -good growth = gram negative -pink = ferments lactose, little acid production -purple/black with/out green sheen = ferments lactose and/or sucrose with acid production -colorless = no lactose/sucrose fermentation (noncoliform)

differential -yellow + bubble = fermentation with gas -yellow, no bubble = fermentation w/out gas -red, no bubble = no fermentation -pink, no bubble = degradation of peptone, alkaline

uses same media s VP test -detects organisms capable of performing mixed acid fermentation -uses a methyl red indicator following incubation -red = mixed acid fermentation -no color = no mixed acid fermentation

uses same media as methyl red test -adding VP reagents oxidizes acetoin and diacetyl -red = acetoin produced -no color = no acetoin

electron transport chain/H2O2 test -bubbles = catalase (no H2O2) -no bubbles = no catalase

paper with reducing agent small paper is purple = cytochrome c oxidase + small paper stays the same = no cytochrome c oxidase

mostly gram negative contains nitrate reductase for anaerobic respiration -gas, nonfermenter = N2 production, + -gas, fermenter = source of gas unknown, reqs reagents -red color after reagents = nitrate -> nitrite, + -no color after reagents = reqs Zn -no color after Zn = nitrate -> nitrite -> other, + -red after Zn = no nitrate reduction, -

poor growth = gram positive bacteria

no lactose fermentation

acetoin was produced, + result

pH indicator, acid/fermentation present

positive result, the bacteria is acid fast -carbolfushin

deep waves

pH indicator, acid

The bacteria is positive for lactose/sucrose -may have green metallic shine

like a sunny side up egg

a donut

looks like coral

long, stringy

coral shaped