The Diversity Of Bacteria And Archaea

Question 1

Rhizobia

Answer 1

Fix nitrogen and form relationships with legumes (plants that bear seeds in pods). Live in nodules formed on the roots of the plant. The plants synthesize leghemoglobin which binds and controls levels of O2. Within the microaerobic environment of nodules the bacteria can fix nitrogen.
They benefit the cell.

Question 2

Bdellovibrio

Answer 2

Highly motile curved rods that prey on E.coli and other gram negative bacteria. When it attacks the strike is so powerful that the prey is propelled a short distance. The parasite attaches and rotates with a spinning motion. Makes digestive enzymes to break down lipids and peptidoglycan resulting in a hole in the cell wall. Lodges into the periplasm and utilizes the preys cellular contents. Oxidizes amino acids and acetate for energy. It increases in length and then divides to form daughter cells that infect new hosts when the prey cell is lysed.

Question 3

Bioluminescent bacteria

Answer 3

Benificial for both
Bacteria gain nutrients while host is able to camouflage.
Bacteria emits light by the enzyme luciferase. It is monitored by quorum sensing. They need high density of bacteria around.
They are al facultative anaerobes

Question 4

Sulfur oxidizing, nitrate reducing marine bacteria

Answer 4

Some marine bacteria store sulfur (energy source) and nitrate (terminal electron receptor). Provides advantage for bacteria because these two things are located in different areas (harder to get). They will always have supply of both. Sulfur - in anaerobic sediments. Nitrate - in waters above.

Thioploca commute between sediments and waters. They form long sheaths so they can travel between both.

Thiomargarita namibiensis: white because sulfur, large diameter, don’t move, rely on disturbances to be in contact with nitrate rich waters.
Usually large organisms are at a disadvantage because there aren’t enough nutrients for its large surface.
Stores sulfur and nitrate

Question 5

Mycoplasma

Answer 5

Lack cell walls, have sterols in membrane that provide what the cell walls do (strength and rigidity).
Looks like fried egg because the center is dense on agar medium
So small it passes through filters and contaminates the media.

Question 6

Sulfur reducing hyperthermophiles

Answer 6

Obligate anaerobes. Use sulfur as a terminal electron receptor. Oxidize organic compounds for energy. Live in sulfee hot springs or hydrothermal vents.
Life is supported by chemolithoautotrophs.

Question 7

Deinococcus radiodurans

Answer 7

Survives radiation. Radiation resistant.

Question 8

Agrobacterium

Answer 8

Genetically engineers plant to their own benefit

Gram negative rod