Effect of SDS on planctonic Acidithiobacillus thiooxidans and bioleaching of sand samples

The inhibition of bioleaching by sodium dodecyl sulphate (SDS), previously used in large scale percolators in Romania (Schippers et al., 2001), was shown for pure cultures of sulphur-oxidizing Acidithiobacillus thiooxidans DSM 622 or German sand samples.A decrease of 25–75% in planctonic cell number from an initial 1010A. thiooxidans cells, counted with a Thoma-chamber 30 min after exposure to SDS concentrations from 0.5 to 10 g/L, suggested a cell lysis. Additionally a release of nucleic acids was found.To apply these results in a more complex habitat, columns filled with aquifer material from an East German lignite mining area containing 1% pyrite were treated. Columns were washed once with 2 g/L SDS and afterwards with rainwater. Most-probable-number determinations of flow-through revealed no growth of iron- and sulphur-oxidizing microorganisms within 26 weeks, while up to 106 cells per millilitre were determined in the control. Elution of sulphate dropped to 25%.

► SDS effect on bioleaching was investigated. ► A lysis of A. thiooxidans in a planctonic high cell density system is suggested. ► Arguments: release of DNA and significant but not complete cell disappearance. ► In sand samples neither sulphur- nor iron-oxidizing microorganisms were detectable. ► Reduced sulphate release by SDS treatment indicated the sensitivity of bioleaching.