L12: Other large Nitrating Storing SOBs

Question 1

Thioploca

Answer 1

• inhabits similar niche as Thio with similar metabolic strategy but is smaller /motile
  *takes up and stores NO3- in large vacoule while in upper zone
  *generated energy via oxidise of So to SO4- (2-) in the upper zone and H2S to SO/SO40 in lower zone
  *TEA in both zones NO3- reduced to NH4
  *C source: CO2 or acetate
  facultative chemolithoautotroph

sheath bacteria that go up and down to get nitrate, then lower to get H2S, can also use O but cannot take O down
*this causes them to accumulate sulfur, lose it going up

Question 2

Beggiatoa

Answer 2

• H2S SOB
  *inhabits oxgyen-sulfide interface so lives throughout gradient
  *prefers O2 as TEA but can also store NO- in vacoules to survive anoxic conditions
  *hetertophs

Question 3

What is the difference between Nitrate and Sulfide

Answer 3

redox potential

Question 4

What does Thioploca core sample look like

Answer 4

*8cm from bacterial mat at an oxygen minimum zone, 1cm thick
*each filament extends into sediment (sulfide source) and water (nitrate source)
*peru

Question 5

Compare Thiomargarite and Thioploca

Answer 5

• energy and electron source in spatially separated zones

Thioploca
*is motile so actively moves between H2S and NO3
*No turbulence so must be motile
*Very large but cannot be large and motile

Thiomaragtive
*passively moves via turbulence
*larger size allows it to store more TEA

Meanwhile Biogotta has one end in both

Question 6

Thiomargaritta cycles

Answer 6

1. Dissimilatory nitrate reduction which leads to denitrification or nitrite ammonification
2. H2 S oxidation (anaerobic) using NO3- as e- acceptor
3. H2 S oxidation (aerobic) using O2 as e- acceptor

Question 7

What system do the SRBs discussed use

Answer 7

DSR

Question 8

Discuss size and shape of bacteria

Answer 8

Larget is thio, smallest is P.ubique
*porportional size difference is very extreme
*smallest are symbionts of obligate parasite/pathogens with reduced genome, hard to cutlure

Question 9

Smallest bacterium

Answer 9

Pelagibacter ubique
* smallest known by volume
*part of Alphaprotesobacteria Pelagibacterales
*has a light driven proton pump called proteorhodpson, it works independalty and is not part of a system