November 13

Question 1

Nosocomial Infection

Answer 1

Health care associated infection

Question 2

Why are nosocomial infections spread?

Answer 2

Low resistance

Rooms with more than one patient

Workers move from patient to patient

Procedures indoduce cuts, punctures to the skin providing a portal of entry for pathogens

Surgery

Use of antibiotics- microbes are constantly exposed to anitbiotics

Question 3

Proteobacteria

Answer 3

Major phyla of bacteria

Most common, most metabolically diverse

Can be chemolithotrophs, chemoorganotrophs, and photoautotrophs

Morphologically diverse: five classes- alpha, beta, delta, gamma, epsilon that are classified by 16S rRNA analysis

Question 4

Phototrophic Proteobacteria

Answer 4

• Oxygenic photosynthesis
• Purple Phototrophic Bacteria

Question 5

Oxygenic Photosynthesis

Answer 5

6CO₂ + H₂O —> C₆H₁₂O₆ + 6O₂

Water is the electron donor

Carbon Dioxide is reduced

Question 6

Purple Phototrophic Bacteria

Answer 6

Anoxygenic photosynthesis, no O₂ is released

-alpha, beta, or gamma

Bacteriochlorophylls and carotenoid: various pigments absorb different wavelengths of ight

Intracytoplasmic membranes: originate from cell membrane, increases surface area for more photosynthetic machinery

Question 7

Purple Sulfur Bacteria

Answer 7

Use H₂S as e- donor to reduce CO₂

Produces S°, stored as globules inside or outside the cell, then is oxidized to sulfate (SO₄^2-) and released into the environment.

Gamma proteobacteria

Found in illuminated anoxic areas of lakes where H₂S accumulates also found in sulfur springs

Question 8

Phototrophic Proteobacteria Examples

Answer 8

Purple Phototrophic Bacteria

a) Purple Sulfur bacteria
b) Purple nonsulfur bacteria

Question 9

Purple Nonsulfur Bacteria

Answer 9

Once thought to be incapable of using sulfur as e- donor

High levels of hydrogen sulfide kill them

Most can grow aerobically in the dark (chemoorganotrophy)

Most can also grow photoheterotrophically: sunlight provides energy and organic carbon source

Alpha or Beta

Question 10

Nitrifying Bacteria

Answer 10

Chemolithotroph (inorganic electron donors) use N compounds

Found in alpha, beta, delta, and gamma

Nitrification

Question 11

Nitrifying Bacteria Examples

Answer 11

1) Ammonia oxidizers (Nitrosococcus)
2) Nitrite Oxidizers (Nitrobacter)
3) Nitrogen-fixing bacteria

Question 12

Nitrification

Answer 12

Oxidation of ammonia to nitrate

Question 13

Nitrate Oxidizers

Answer 13

Nitrobacter

Usually have internal membrane systems that house key enzymes including: ammonia monooxygenase and nitrate oxidase (nitrite to nitrate)

Question 14

Nitrogen Fixing Bacteria

Answer 14

NH₄⁺—-> NO₂^- —> NO₃^-

Found in soil and water

Common in habitats with lots of ammonia, where lots of proteins decompose (sewage treatment facility)

Question 15

Sulfur-Oxidizing Bacteria

Answer 15

Chemolithotroph (uses reduced sulfur compounds)

Two classes: neutrophiles and acidophiles

Examples: Thiobacillus and Beggiatoa

Question 16

Thiobacillus

Answer 16

Produce sulfuric acid, electron donor is H₂S, S°

Question 17

Beggiatoa

Answer 17

Filamentous gliding bacteria, found in H₂S rich environments such as hydrothermal vents, mud in lakes, sewage polluted H₂O, swamp plant roots (Cattails: detoxifies H₂S around the roots), flocs in sewage treatment (causes bulking-no settling of particulate matter)

Question 18

Methanotroph

Answer 18

Use 1C compounds as e- donors and as a source of carbon

Widespread in soil and water

Obligate aerobes

Two types: Type 1 and Type 2

Both types use methane monooxygenase, incorporates one O from O₂ into methane to produce methanol

Bot have extensive internal membranes to increase surface area from methane oxidation