Spring thermal water from different origin and mineral composition was evaluated to prepare the culture media for Thermus thermophilus HB27. The growth and lipolytic activity was evaluated and analyzed as function of ion concentrations in the culture media. Mineral composition of the water does not affect the maximum growth of T. thermophilus HB27. Nevertheless, the lipolytic activity was strongly enhanced when Burgas and Laias spring thermal water were used. This improvement cannot be obtained formulating culture media by adding to distilled water the main ions present in Burgas water separately. Thus, Ca(2+), Mg(2+) neither affect growth nor enzyme production and HCO(3)(-) inhibits maximum biomass and intracellular lipolytic activity productions but had a clear positive effect on extracellular lipolytic activity. These results suggest that a different or more complex ionic composition in the culture medium (as the present in the Burgas hot spring water) is necessary to enhance the lipolytic activity production in T thermophilus HB27. (c) 2008 Elsevier Ltd. All rights reserved.