Abstract: This invention relates to a process for sulfur removal from gas streams by contacting an active culture of photosynthetic sulfur bacteria with reductive sulfur compounds and carbon oxides in the gas stream under substantially anaerobic conditions with irradiation by electromagnetic energy and cultivating the bacteria to form elemental sulfur and organic carbon compounds. The process is particularly suited for removal of hydrogen sulfide from acid-gas streams and from natural or raw pipeline gas with greater than 95 percent and usually greater than about 98 percent sulfur removal from gas streams. The process is operable with gas streams of very low hydrogen sulfide content of about 0.1 and less Mole percent and gas streams of high hydrogen sulfide content. The process utilizes Chlorobium bacteria to produce elemental sulfur and organic carbon compounds which may be advantageously utilized to produce hydrocarbon fuels.