Lecture 17 Gram Negative Bacteria

Question 1

List Characteristics of Proteobacteria

Answer 1

1. metabolically diverse
2. distinct morphology
3. many environmental members
4. many important pathogens

Question 2

What are some metabolic characteristics of Proteobacteria?

Answer 2

Phototrophs, chemoorganotrophs, chemolithotrophs

Heterotrophs, Autotrophs, Diazotrophs

Question 3

Provide examples of important environmental members and pathogens within Proteobacteria.

Answer 3

Nitrifying bacteria
iron and sulfur bacteria
methanotrophs

pathogens like Rickettsia are significant members.

Question 4

Describe the cellular morphology of Caulobacter and Hyphomicrobia.

Answer 4

exhibit stalked/prosthecate cell morphology and budding cell division

swarmer cells differentiate into sessile stalked cells, attaching to surfaces via Tad pili and developing holdfast

Question 5

How do swarmer cells differentiate?

Answer 5

They lose their flagellum and pili. Attach to the surface and grow stalk

Question 6

Who are the predators of gram-negative bacteria?

Answer 6

Bdellovibrio

Question 7

What is the life cycle of Bdellovibrio and what do they do?

Answer 7

alternate between predatory and reproductive phase

utilize host contents (carbon,nitrogen, energy sources)

employing fatty acids and nucleotides directly in biosynthesis

undergoes filamentous growth with multiple fission

Question 8

Name some features of nitrifying bacteria and their significance

Answer 8

extensive intracytoplasmic membrane, great surface area for metabolism –>

needed to oxidize large amounts of substrate to fuel CO2 fixation

Key organism in the nitrogen cycle, important in agriculture, waste water

Question 9

Name some Ammonia oxidizing bacteria and nitrite oxidizing bacteria

Answer 9

AOB: Nitrosomonas, Nitrosospira, Nitrosococcus

NOB: Nitrobacter, Nitrococcus, Nitrospira

Question 10

Describe features of Rickettsia and its association with diseases.

Answer 10

-Intracellular parasites associated with genome reduction
-zoonotic pathogens

How? enter host through insect saliva and taken up by phagocytosis

Question 11

What is known and unclear about the origin of mitochondria?

Answer 11

mitochondria come from the α-PB

Lineage is unclear because of limited genome size
Related to Rickettsia or purple non-sulfur bacteria?

Intracytoplasmic membrane (ICM) in rhodobactterales resembles mitochondrial cristae