EN3: enrichment and isolation of purple non-sulfur bacteria

how are these bacteria purple?

complementation of carotenoid pigments and unique chlorophyll (chlorophyll a and b)

G-9 is a carotenoid-less mutant. what color is bacteriochlorophyll a?

blue, carotenoid makes orange pigment

purple non-sulfur bacteria are…

photoautotrophs and photoheterotrophs(carbon from CO₂ and carbon from glucose respectively)

purple non-sulfur bacteria can grow in the dark via…

aerobically and anaerobically(fermentation or respiration)

purple non-sulfur bacteria photometabolism occurs…

anoxygenically

bacteriochlorophyll has higher/lower redox potential than O₂/H₂O couple

lower

can H₂O serve as an electron donor?

no as bacteriochlorophyll has a lower redox potential than O2/H2O couple

how are we incubating the purple non-sulfur bacteria?

under light, anaerobically to prevent respiration

what are the possible sources of non-fermentable organic carbon?

• citrate

• malate

• benzoate or cinnamate

What is going to be added to prevent the P680 center(PS II) of cyanobacteria?

DCMU

what is another way that prevents the growth of cyanobacteria?

high organic concentration

R. palustris is able to use benzoic acid or cinnamic acid as a carbon source, but the process is strictly…

anaerobic and light dependent

describe the photosynthetic processes of purple non-sulfur bacteria: how electrons are lost in P870, how are electrons replaced, and how is energy gained for oxygen fixation?

• lose electrons: light excites electrons in P870 → donates electrons to ETC to make NADPH

• replace electrons: electrons are replaced by hydrogen gas or hydrogen sulfide oxidation

  • electrons are then passed to C2 then P870

• carbon fixation: energy comes indirectly from light that helps turn ADP into ATP

  • happens through ETC

  • electrons from NADPH

  • H2 or H2S has to be electron donor as the reduction potential of P870 is lower than water

does purple non-sulfur bacteria produce oxygen?

no

what is the hallmark photo metabolism of purple non-sulfur bacteria?

anoxygenic