Growth inhibition of Thiobacillus thiooxidans by metals and reductive detoxification of vanadium (V)

Summary Vanadium (V), molybdenum (VI), and chromium (VI) have all been found to inhibit the growth of Thiobacillus thiooxidans ATCC 8085. Exponentially growing cultures of the microorganism effectively reduce vanadium (V) to the relatively inocuous vanadyl ion, vanadium (IV), by a first order process with a half-life of about 10 h. Concentrations above the reducing capacity of the culture subsequently prevent further microbial growth. The growth of T. thiooxidans is also inhibited by both molybdate and chromate which can prevent growth in the concentration range 2 to 5×10^–4M. These metal toxicities may play a role in curtailing the growth of this organism in microbially assisted leaching operations.