Photoautotrophs Studies on microbial ecology associated with
phototrophic bacteria have shown that a species of green sulfur
bacteria (GSB) Cholorobium limicola (originally called
Cholorobium limicola forma thiosulfatophilum (Larsen 1952))
is the most suitable for sulfide removal and satisfies the criteria
for a desirable bacterium (Syed and Henshaw 2003).
Cholorobium limicola is capable of oxidizing sulfide to
elemental sulfur, requires only light, CO2
, and inorganic
nutrients for growth and is strictly anaerobic. GSB are nonmotile
and deposit elemental sulfur extracellularly. This feature
makes GSB suitable where the recovery of elemental sulfur
from sulfide-containing wastewater is desired. The overall
photochemical reaction by which GSB oxidizes S2- to S0
while
reducing CO2
to carbohydrates is (van Niel 1931):