Thiodictyon is a genus of gram-negative bacterium classified within purple sulfur bacteria (PSB).

[7][5] GTDB reports that several whole genomes from metagenomic samples, not yet named, are also available, clustering into three additional species-level groups.

Its chemocline, which occurs at approximately 12 m, is quite narrow and has high concentrations of sulfide, sulfate, oxygen and light.

[9] A turbidity maximum also correlates with the chemocline, and this is caused by high concentrations of anaerobic phototrophic sulfur bacteria.

is a sulfate reducing and sulfur disproportionating bacteria found in both mixed culture and within the natural environment.