Question

Looking for a microbiology Lab Final Cheat sheet, we are allowed to bring a double sided 8x12 in. Someone in my class found hers online last quarter and I can't seem to find one

Answer 1

Simple stain- basic(+)charge in methylene blue stains bacteria and negative stain acidic(-)charge in nigrosine stains background/no heat fix.

Heat fix-to keep the bacteria from moving, heat fixing for too long could kill the bacteria.

Gram stain-false negative can occur from over/under decolorization, false positive can occur from safranin left on too long

Endospore-light red cells w/ dark green spores, diff result can occur from slide held over steam for too long/missing a stain

Motility-no heat fix because that would kill the bacteria, keep light to a minimum, hanging drop/wet mount

Phenyethyl Alcohol Agar (PEA)-gram positive grows well, alcohol intolerance

Mannitol Salt Agar (MSA)- staphylococcus & microbiota grow well, yellow around bacteria(mannitol fermentation)

MAC-against gram-positive the most, favor gram-negative, red coloration of bacterial growth from pH decrease –lactose fermentation

EMB-against gram-positive, test water safety, pink coloration due to acid formation

Aerobe-requires oxygen to survive, anaerobe-cant grow wth presence of oxygen around, facultative-can grow with or without oxygen but prefers one, microaerophile- needs only a small amount of oxygen, pink=presence of oxygen

Cardinal temperature- lowest, highest and optimal temperature an organism can live at, stentothermal-narrow range, eurythermal-wider range

mesophilic-range of cold&hot, psychrophilic-cold temp preferred, thermophilic-high temp preferred, obligate-only at high or low, specific places, facultative-best at either high or low, can at either

Oxidase-dark blue color is positive, catalase-release of oxygen gas (bubbling) is a positive result

alpha hemolysis-incomplete form partially degrades RBC, produces green zone(partial clearing) around bacterial growth

beta hemolysis-complete destruction of RBC's, clearing zone 2-4 times larger than the diameter of the colony

gamma hemolysis-absence of hemolytic activity, lacks any type of clearing zone

coagulase-clot formation within 4 hours is a positive result, absence within 24 hours is negative, good for staphylococcus species

novobiocin-put disc onto the center of each culture, sensitivity to the antibiotic will result in clearing zone around the disc, good for staphylococcus species

Casein-milk agar plate, clearing zone(loss of opacity due to hydrolysis of casein) around bacteria is positive

DNA-DNase agar plate, when DNA is hydrolyzed methyl green is released clearing zone is a pink color

Esculin-bile esculin slant, a dark precipitate is positive, formed when Fe3+ in medium reacts with esculetin

Lipid-egg yolk agar plate, clearing zone(loss of opacity due to hydrolysis of lipid) around bacteria is a positive result

Starch-starch agar plate, cover surface with grams iodine, clearing zone of reagent around bacteria is evidence of starch hydrolysis, the blue color is produced when starch reacts with iodine

Urea-urea broth, a dark pink color associated w pH increase due to the production of ammonia during urea hydrolysis

Carbohydrate fermentation-phenol red sugar broths, evidence of fermentation of sugar to acid (indicated by yellow color) and/or CO2(bubble collected in an inverted tube)

nitrate reduction-add nitrate A&B to tube, red color indicates presence of nitrate in medium, pos result. If no color change then add zinc dust, red color indicates reduction of nitrate still present in medium-negative result. Lack of color change indicates microbe reduced nitrate to nitrite and then to N2 gas-positive result. If zinc dust is added before A&B you cant tell which reagent the color change is from

IMViC-

1. MR-VP broth-add 20 drops of Barritt's reagent A & 20 drops of baritts reagent B, shake vigorously, appearance of red color indicative of acetoin is positive, rxn can take up to 2 hours, no color after this time is negative result. Add 4 drops of methyl red to different portion, the culture will immediately turn red if pos for fermentation of glucose to mixed acids. If methyl red is positive then other is likely positive also

2. Simmons citrate agar-blue color is indicative of increased pH associated with the metabolism of citrate.

3. Trypticase soy broth- add 10 drops of Kovac's reagent, a change in the reagent layer to a pink color is positive result, indicating the presence of indole from tryptophan hydrolysis

TSI triple sugar iron agar slants-(glucose, sucrose+lactose, ferrous sulfate, phenol red, cysteine, Na thiosulfate).

Red throughout medium=no fermentation.

Yellow throughout medium=fermentation of glucose and lactose and/or sucrose.

Red slant+yellow butt=fermentation of glucose only.

Cracks or lifts in agar=gas production associated with fermentation. Black

precipitate=production of H2S due to sulfur reduction (AA breakdown).

Phenylalanine deamination-test tubes for the formation of phenyl pyruvic acid by permitting four or five drops of a 10% FeCl3 solution to run over the slants, a green color is a positive result

Amino acid decarboxylation- arginine, lysine, and ornithine decarboxylase broths. Overlay the inoculated broths with sterile mineral oil to a depth of about ¼ inch and screw caps tightly. Observe at 24 hr and 48 hr, pos rxn is a purple-blue to lavender-blue color, negative reaction is yellow. Examine the tube for observable growth (turbidity). The organism must first ferment the small amount of glucose in medium to create the acidic conditions necessary for decarboxylation to occur, in pos rxn the medium should first turn yellow then back to purple again

NOTE-mineral oil is on top because its acidic and anaerobic so that conditions can happen.