Anyoxygenic phototrophs: enrichment of purple non sulfur bacteria

What are phototrophs?

Organisms that can use light as an energy source

What are anooxygenic phototrophs?

An organism that uses light for energy, but does not produce molecular O2 as waste (because it does not have a photosystem II to use water to fix CO2 and instead uses other molecules like H2s)

What is the largest and most diverse group of anooxygenic phototrophs>

Purple non-sulfur bacteria

What are the major genera of purple non-sulfur bacteria?

Rhodobacter, Rhodospseudomonas, and Rhodospirillum

What are the gram stain results and cell morphology of purple non-sulfur bacteria?

Gram negative with cells shapes ranging from short coccobacilli to straight rods to helical rods

Which genera of purple non sulfur bacteria grow via budding than by binary fission?

Rhodopseudomonas

True or false: many purple nonsulfur bacteria are motile due to having polar or sub-polar flagella?

True

What are chemoheterotrophs?

Organisms that gain their energy and carbon source from organic molecules

Purple nonsulfur bacteria are capable of chemoheterotrophic growth by respiration when?

Cultivated aerobically

What will Rhodopseudomonas look like under darkfield or phase-contrast?

Irregular rods with swollen tips (budding)

What will Rhodospirillum look like under darkfield or phase-contrast?

Helical shaped cells

Pond mud will be incubated in the light in sealed containers containing succinate as a sole source of organic carbon. What's the purpose sealing the pond mud and what is the purpose of using succinate?

1) Obligate anaerobes present will be killed or strongly inhibited by initally aerobic conditions

2) the dissolved oxygen will consumed by aerobic heterotrophs (ie. purple nonsulfur bacteria) results in fully anaerobic conditions

3) Succinate is a poor substrate for fermentation so purple non sulfur bacteria should outcompete ferementative heterotrophsbc it can grow phototrophically.

Purple non sulfur bacteria is a

Facultative anaerobe