Effect of Water Potential on Growth and Iron Oxidation by Thiobacillus ferrooxidans

Abstract

The effect of water potential on the growth of two strains of Thiobacillus ferrooxidans was determined by adding defined amounts of sodium chloride or glycerol to the culture medium. The two strains differed slightly, and the most tolerant strain had a minimum water potential for growth of-15 to-32 bars when sodium chloride was used and-6 bars when glycerol was used. In another approach, the limiting water potential was determined by equilibrating small amounts of culture medium with atmospheres of relative humidities equivalent to specific water potentials, and the ability of the organism to grow and oxidize ferrous iron was determined. Under these conditions, which are analogous to those which might control water potential in a coal refuse pile or copper leaching dump, the lower limit at which iron oxidation occurred was-23 bars. The water potential of some coal refuse materials in which T. ferrooxidans was present were determined, and it was found that the water potentials at which the organism was active in these habitats were similar to those at which it was able to grow in culture. However, marked variation in water potential of coal refuse materials was found, presumably due to differences in clays and organic materials, and some coal refuse materials would probably never have water potentials at which the organism could grow. Some literature on the water potentials in copper leach dumps is reviewed, and it is concluded that control of water potential is essential to maximize the success of leaching operations. Because adequate drainage is necessary in a leach dump to ensure sufficient aeration, in many cases water availability in leach dumps may restrict the development of the bacterium necessary for the process.

Extremophile microbiomes in acidic and hypersaline river sediments of Western Australia

“…Capacities of salt tolerance and Fe(II) oxidization of acidophiles have been studied on several strains used for bioleaching (Razzell and Trussell, ; Brock, ; Huber and Stetter, 1989; 1991; Suzuki et al ., ; Simmons and Norris, ; Nicolle et al ., ; Zammit et al ., ; Korehi et al ., ). Although knowledge about the physiology of acidophilic microorganisms under hypersaline conditions is scarce, even less is known about microbial community structures and their potential roles in biogeochemical processes in such acidic and hypersaline environments.…”

Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic ‘Thiobacillus prosperus’

“…Salt (NaCl) tolerance in ferrous-iron-oxidizing acidophiles is of considerable interest in the context of potential biomining operations where chloride is present in the ore or where only saline process water might be readily available. Acidithiobacillus ferrooxidans, the most intensely studied acidophilic, ferrous-iron-oxidizing bacterium, is not tolerant of salt and many strains are totally inhibited by 1 % (w/v) NaCl (Razzell & Trussell, 1963;Brock, 1975). The salt-tolerant, iron-and sulfur-oxidizing 'Thiobacillus prosperus' (Huber & Stetter, 1989) was isolated from close to marine hydrothermal vents of Vulcano (one of the Aeolian Islands), but has been the subject of little work beyond its original description.…”

Ferric iron reduction by sulfur- and iron-oxidizing bacteria

“…The culture of T. thiooxidans was obtained from J. Shiveley of Clemson University. The T. ferrooxidans culture had been isolated on ferrous iron in this laboratory for some previous work (3) and was adapted for growth on elemental sulfur for the present study. Both Thiobacillus cultures were maintained at room temperature in Erlenmeyer flasks and were shaken gently with a Burrell wrist-action shaker.…”