Toxicity of membrane filters to Thiobacillus ferrooxidans

Membrane filters of different origins and types contain substances that are toxic to Thiobacillus ferrooxidans in media where Fe2+ constitutes the source of energy. The toxic principle(s) can be almost completely removed by heating to 115–120 °C or by leaching in boiling water. The damage of the membranes which follows from these treatments makes the membranes useless for ordinary filtration. It seems then that the development of a standard quantitative method using ferrous iron agar for the enumeration of chemolithotrophic iron‐oxidizing bacteria requires further attention.