Like green sulfur bacteria, purple sulfur bacteria are also capable of symbiosis and can rapidly create stable associations between other purple sulfur bacteria and sulfur- or sulfate-reducing bacteria. These associations are based on a cycle of sulfur but not carbon compounds. Thus, a simultaneous growth of two bacteria partners takes place, which are fed by the oxidation of organic carbon and light substrates. Experiments with "Chromatiaceae" have pointed out that cell aggregates consisting of sulfate-reducing Proteobacterium "Desulfocapsa Thiozymogenes" and small cells of "Chromatiaceae" have been observed in the chemocline of an alpine mermocitic lake.