Microbiology lab quiz 4

sterile, bacteria

the inside of the apple or carrot is ___, but the outside has ____

Brilliant Green Bile broth (BGB)

indicator of coliforms

selective for coliforms

brilliant green - inhibits non-coliforms

bile - inhibits Gram positive bacteria

Differential for coliforms

contains lactose → acid + CO2

coliforms

Gram negative

ferment lactose to produce acid and gas

CO₂

Yeast ferments sugar to produce ___, which causes the bread to rise

Lactobacillus

ferments lactose to produce acid

creamy consistency

acid causes milk proteins to coagulate to produce a _____

Lactobacillus

Gram positive coccobacilli

Streptococcus mutans

forms long glucose polymers on teeth producing plaque

acid

Lactobacillus under plaque ferments fructose to produce ___

Snyder’s agar

detects Lactobacillus

selective for Snyder’s Agar

low pH block growth of other species

differential for Snyder’s Agar

Glucose fermentation lowers pH and Bromocresol green turns yellow below pH 4.8

low chance of tooth decay

3 day yellow

tooth decay not likely

still green

standard plate count (SPC)

to count the total number of bacteria in milk

Violet Red Bile (VRB)

used to count the total number of coliforms in milk

pasteurization

heating to kill pathogens

more

Phosphate enzyme in raw milk is ___ resistant to heat than pathogens

then pathogens are destroyed too

if phosphatase is destroyed…

blue

positive color for the phosphatase enzyme