How bacteria can survive in acidic, metal rich environments
Acid-loving bacteria thrive in sour, acidic places and can help to dissolve metal. Therefore they are often used for industrial metal extraction. In her doctoral thesis "Growth and Survival of Acidithiobacilli in Acidic, Metal Rich Environments" Stefanie Mangold, Umeå University, has explored basic mechanisms of these very special bacteria.
"Acidithibacilli are very powerful, for example one forth of the worlds copper is extracted with these microorganisms. But they can also cause environmental problems, for example with abandoned mine sites. That's why basic research into these bacteria is important. If we understand the processes we may also at some stage control pollution problems better," says Stefanie Mangold, the Institution of Molecular Biology, Umeå University.
The special property of acid-loving bacteria is that they can live in extremely acidic places highly polluted with metals, where no other organisms can survive. They also have a natural capacity to solubilize metal ores and are often used for industrial metal extraction.
To gain insight into how these microorganisms can thrive in such an unfriendly environment, Stefanie Mangold has investigated metabolism, metal resistance and pH homeostasis with focus on two model organisms, Acidithiobacillus caldus (At. caldus) and Acidithiobacillus ferrooxidans (At. ferrooxidans).
Pathways of how At. caldus can break down sulfur compounds to gain energy were suggested. This might eventually help to optimize industrial metal extraction as the degradition of sulfur compounds is an important step in the breakdown of metal ores.
Furthermore, it was studied how At. ferrooxidans can grow without using oxygen, which is of interest for metal extraction in large piles of metal ore where anaerobic zones can exist. Finally the knowledge of how these microbes can survive stress due to metals and acid might also help in fine tuning industrial processes.