Susceptibility of halobacteria to heavy metals

Abstract

Sixty-eight halobacteria, including both culture coUection strains and fresh isolates from widely dift'ering geographical areas, were tested for susceptibility to arsenate, cadmium, chromium, cobalt, copper, lead, mercury, nickel, silver, and zinc ions by an agar dilution technique. The culture collection strains showed dift'erent susceptibilities, clustering into five groups. Halobacterium medilerranei and Halobacterium volcanii were the most metal tolerant, whereas Haloarcula californiae and Haloarcula sinaiiensis had the highest susceptibilities of the culture collection strains. Dift'erent patterns of metal susceptibility were found for all the halobacteria tested, and there was a uniform susceptibility to mercury and silver. All strains tested were multiply metal tolerant.