[Isolation of transcription promoters from Thiobacillus ferrooxidans and T. acidophilus and its introduction by conjugation to T. intermedius].

The chemolithotrophic acidophilic bacteria, Thiobacillus ferrooxidans is considered as the most important microorganism in relation to copper and uranium bioleaching ability. Since T. ferrooxidans is a strict chemolithotrophic microorganism, its genetic manipulation is a very hard task. Until now, all efforts have been unsuccessful. Therefore, we decided to approach the problem in steps, trying initially to manipulate some T. ferrooxidans related strains. We chose Thiobacillus acidophilus that shares its habitat with T. ferrooxidans and Thiobacillus intermedius, for its heterotrophic nature that makes them easier to grow and suitable for heterologous conjugation. The main objective of this work was directed towards the isolation and characterization of transcription promoters from T. acidophilus and T. ferrooxidans genomic DNA. Four different promoters from T. acidophilus and four from T. ferrooxidans were isolated and sequenced. In order to test their functional capacity in bacterial systems different from E. coli, they were subcloned and transferred to other bacteria. One of these recombinant plasmids was successfully transferred to T. intermedius and from it to Ps. putida. The subcloned promoter was able to confer streptomycin resistance to Ps. putida.