Quiz 2

Question 1

Propionic bacteria

Answer 1

Aeroduric obligate anaerobes. Catalase positive. Gram positive, rod-like shape. Slow growing, use variety of carbon sources

Question 2

Catalase test

Answer 2

Enzyme protects against toxic oxygen species. Positive for aerobes and facultative anaerobes. Negative for obligate anaerobes. Induced when grown aerobically, not present if grown anaerobically (expose culture to O2 at least 15 min before testing)

Question 3

Acetoin (Voges-Proskauer) Test

Answer 3

Tests butanediol fermentation pathway to ferment glucose. (used on micrococcus)

Question 4

Nitrate Reduction Test

Answer 4

NO3- -> NO2- -> N2 + NH3

Some bacteria only go from NO3 to NO2, some can go all the way to N2. Tests the ability of denitrification. (Reducing nitrate to nitrogen gas) If no color change, either no denitrification or goes all the way to N2. Adding zinc forces from NO3 to NO2. If color change, then it isn’t doing anything. If still no color change than it’s going all the way

Question 5

Oxidase Test

Answer 5

Identified cytochrome c oxidase present (etc in some aerobic respirers). ( we did to micrococcus)

Question 6

Purple Non-Sulfur bacteria

Answer 6

Gram - rods/spirals. Anoxygentic photo trophy capable of growing chemeheterotrophically. Inhibited by H2S. Grow in bad carbon source O2 present media so obligate aerobes die, then change to anaerobic where the ability to phototrophic grow gives them ability to outcompete fermenting heterotrophs.

Question 7

Pseudomonas’s

Answer 7

Gram - rods, obligate respirers, some can anaerobic with denitrification, produce pigments that are or aren’t fluorescent. Rapid metabolism, oxidase +

Question 8

Endospores: Bacillus and clostridium

Answer 8

Gram + rods,
Bacillus: facultative anaerobe (cat+
Clostridium: obligate anaerobe (aeroduric) (cat-)
Sporangium: mother and spore

Question 9

Gram + cocci (micrococcus staphylococcus

Answer 9

Micrococcus: matte buttery colony, salt tolerant, obligate aerobe
Staphylococcus: facultative anaerobe, acid on glycerol, aureus and epidermidis on mannitol.

Question 10

Catabolite repression

Answer 10

Glucose as a nutrient rich media represses the expression of catabolic pathways for less favorable carbon sources (like agarase for agar degrading)