Re: Where is pleurococcus most likely to grow and why?

Pleurococcus is a phototrophic bacterium in the family Chromatiaceae. It falls in the genus Lamprocystis (brilliant bag). Bergey's Manual lists it as Pleurococcus roseo-persicina (Kutzing) Rabenhorst 1868. The microbe should have a rosy peach coloration as per its designation. I have very little information on this particular species, but can give you relevant information about other closely related organisms.

The Chromatiaceae comprise the purple sulfur bacteria. These organisms are obligate phototrophs (must photosynthesize to live) and they are strictly anaerobic. Thus, their photosynthesis is anoxygenic (does not produce oxygen). Remember that in plant-like oxygenic photosynthesis light excites electrons and then energy is captured as these excited electrons move down the potential energy gradient, until the terminal electron acceptor NADP+ is reduced to NADPH. The electrons that get excited come from water. Thus, water is split, electrons are extracted, and oxygen is released. The purple sulfur bacteria don't extract electrons from water. They extract electrons from hydrogen sulfide. Instead of releasing oxygen, they release sulfur.

The purple sulfur bacteria require hydrogen sulfide and light to grow. Thus, they can be found in mud and stagnant water containing sulfides and exposed to light. An example would be a sulfur spring. One can look for them in shallow freshwater ponds or ditches. Near hot springs, green sulfur bacteria tend to be at the highest sulfide concentrations, followed downstream by the purple sulfur bacteria. Many of these species are thermophiles. Look for pink to purple-red blooms that may form profuse patches on dead leaves or mud surfaces. Stratified lakes will also have a layer containing the purple sulfur bacteria, again because sulfide concentrations are right and there is enough light. Waste stabilization ponds may harbor these microbes as well. The "beach sulfurita" habitats of salt marshes are also rich in sulfides.

Admin Note: A search at Altavista for Pleurococcus located further information on habitats in which they may be found if you wish to learn more..

-L. Bry, MadSci Admin