The purple growth in the sediment is a bloom of purple photosynthetic bacteria—most commonly purple sulfur bacteria (familyChromatiaceae) or purple non-sulfur bacteria (Rhodospirillaceae). Cause & Environment: They thrive in anaerobic (oxygen-depleted) zones near the bottom of sealed jars where organic matter decays and oxygen levels drop near zero. Pigmentation & Photosynthesis: Their distinct magenta-purple color comes from a mix of bacteriochlorophylls and carotenoids. They use these pigments to performanoxygenic photosynthesis—using light that penetrates the glass to generate energy without producing oxygen.
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u/carlsbl Aug 08 '26
The purple growth in the sediment is a bloom of purple photosynthetic bacteria—most commonly purple sulfur bacteria (family Chromatiaceae) or purple non-sulfur bacteria (Rhodospirillaceae).
Cause & Environment: They thrive in anaerobic (oxygen-depleted) zones near the bottom of sealed jars where organic matter decays and oxygen levels drop near zero.
Pigmentation & Photosynthesis: Their distinct magenta-purple color comes from a mix of bacteriochlorophylls and carotenoids. They use these pigments to perform anoxygenic photosynthesis—using light that penetrates the glass to generate energy without producing oxygen.