Micro Lab Quiz 4

Positive catalase

Observation of bubbles with hydrogen peroxide

Negative catalase

No bubbles with hydrogen peroxide

What does catalase do?

Break hydrogen peroxide into water and oxygen

What types of bacteria have catalase?

Obligate anaerobes and facultative anaerobes

Positive oxidase

Purple within 30 seconds

Negative oxidase

No color change

What enzyme does the oxidase test look for

cytochrome c oxidase

Positive coagulase

Clumping/clotting

Negative coagulase

No clumping/clotting

Advantage of coagulase activity

Causes the clotting of blood plasma, surrounding the bacterium with a protective fibrin clot

Positive urease

Pink color

Negative urease

Orange color

How does the urease test work

Urea is broken down into ammonia which makes the phenol red alkaline

Steps for chemical transformation

Purpose of using selective media for transformed bacteria

Selects for bacteria that uptook the plasmid containing amp resistance and also the AraC activates the GFP

How do you know if GFP is being expressed

Fluorescence of the green variety

Genes in the pGLO plasmid

Coliforms

Intestinal bacteria that ferment lactose and produce CO2, evidence of fecal contamination in water

What does MPN stand for

Most probable number, includes presumptive, confirmed, and completed

What MPN tests were performed

Presumptive and completed

Presumptive MPN test

Durham fermentation tubes with lactose, looks for lactose fermentation (yellow) and CO2 production (bubble)

Completed MPN test

EMB plate inoculated, coliforms form black colonies

How to interpret # coliforms per 100ml

Ingredients of Snyder agar

Positive reaction in snyder agar

Presence/absence Colilert test

What enzymes break down ONPG and MUG

How does heterotrophic count determine potability