BIOMINING

Microbes useful in metal recovery


The microbes that are suitable and useful for metal recovery differ depending upon the temperature of the metal recovery process. At 40°C, the most important microbes are Gram negative bacteria belonging to genera Acidithiobacillus and Lactospirillum, which include
 (i) iron and sulphur oxidizing At. ferrooxidans,
(ii) sulphur oxidizing At. thiooxidans and At. caldus, and
 (iii) iron oxidizing L. ferrooxidans and L. ferriphilum.
At 50°C, the suitable biornining microbes include At. caldus, some species of the genus Leptospirillum, and some Gram negative bacteria including the members of the genera Sulphobacillus and Acidimicrobium, and at 70°C, the useful biomining microbes are members of the group archaea (Sulphobolus and Metallophaera). Improvement of bacterial strains for enhanced rate of leaching of metals is also being attempted for several of these bacteria.