It appears that arsenate reduction by the Desulfovibrio strain Ben-RA is catalyzed by an arsenate reductase that is encoded by a chromosomally-borne gene shown to be homologous to the arsC gene of the Escherichia coli plasmid, R773 ars system.
Gram-negative bacteria | Gram-positive bacteria | Sulfate-reducing bacteria | Siderophilic bacteria | Shown above as a result of a 7 week period where the columns have been allowed to grow algae, cyanobacteria and other bacterial colonies. Of specific interest are the red regions of the middle column, indicative of purple non-sulfur bacteria (e.g. ''Rhodospirillaceae | gram-positive bacteria | ''E. coli'' bacteria | Coliform bacteria | arsenate |
Chemist Steven A. Benner has expressed doubts that arsenate has replaced phosphate in the DNA of this organism.
Sulfate-reducing bacteria convert sulfates to toxic hydrogen sulphide gas; they are killed by exposure to air, but the moist, airless, carbon-containing environment in a landfill is a good habitat for them.