Strain variability and the effects of organic compounds on the growth of the chemolithotrophic bacterium Thiobacillus ferrooxidans

The effects of naturally-occurring organic compounds on ferrous iron oxidation by the bacterium Thiobacillus ferrooxidans were examined with a view to using these compounds to treat or prevent acid mine/rock drainage. The compounds glucose, cellobiose, galacturonic acid, and citric acid were added to the growth medium of five different strains of the bacterium and growth studies were done to determine whether or not strain differences existed with respect to organic compound sensitivity. The effects of these compounds were compared to the effects of sodium dodecyl sulfate (SDS) an anionic detergent. Each of the compounds tested had an inhibitory effect on the strains of the bacterium and sensitivity to these compounds was strain dependent. All strains appeared to be equally susceptible to SDS. Inhibitory concentrations ranged from 70 mM to > 280 mM for glucose, 7.5 mM to 150 mM for cellobiose, 20 mM to 230 mM for galacturonic acid, and 50 mM to 130 mM for citric acid. SDS effectively inhibited iron oxidation for all strains at a concentration of 0.3 mM, the lowest concentration tested. Some naturally-occurring organic compounds, therefore, might be candidates for the growth control of T. ferrooxidans.