BACKGROUND: Low substrate (11612) availability restricts microbial sulfate reduction when H-2 is used as an electron donor. In order to enhance hydrogenotrophic sulfate conversion, Desulfovibrio vulgaris Hildenborough (DvH) cells permeabilized with ethanol were used as whole-cell biocatalysts. RESULTS: Cell growth was retarded after permeabilization. The maximum ethanol percentage for the recovery of cell proliferation was 15% (v/v) when permeabilization process duration was 30 min at 4 degrees C. Cells treated with 10% ethanol achieved 1.7-fold measurable hydrogenase activity compared with the control, while hydrogenase activity decreased remarkably with further increase in ethanol percentage. The 10% ethanol-treated cells were also shown to have the highest metabolic activity, 2.31-fold higher than the control. The accelerated metabolic activity was resulted from the enhancement of accessibility to substrate and product efflux due to increased permeability of the cell envelope when 10-15% ethanol was used High ethanol percentages caused cytoplasm leakage and interruption of the electron transfer chain and consequently loss of metabolic activity. CONCLUSION: The utilization of DvH cells permeabilized by 10-15% ethanol solutions with both cell viability and ability to reproduce being maintained promoted hydrogenotrophic sulfate reduction. These preliminary data may contribute to an enhancement of the bioprocess in sulfidogenic reactors. (C) 2009 Society of Chemical Industry