Study of bacterial sensitivity in zinc sulfate solutions by microcalorimetry

Abstract

Zinc sulfate is an inorganic compound and dietary supplement. It has shown antimicrobial effects on certain pathogens and may contribute to the treatment or prevention of infections. In this study, the bacterial growth of Pseudomonas aeruginosa, which is a pathogen involved in several life-threatening infections to the human body, is assessed by microcalorimetry using different concentrations of zinc sulfate. Bacteria growth monitoring has been demonstrated using microcalorimetric techniques. Dissolutions of zinc sulfate were prepared with concentrations from 0 to 250 mM. A suspension of 106 CFU mL−1 of Pseudomona aeruginosa and as a culture medium, a liquid soya-casein-digested liquid were used. The measurements were carried out in a Calvet microcalorimeter at constant temperature of 309.65 K. The reference cell was filled with 6 mL of culture medium, 1 mL of the metallic dissolution, and 1 mL of mineral-medicinal water. In the experimental cell, the latter was replaced by the bacterial suspension. The data were collected by a data acquisition and processing system, at intervals of 22.2 s for 48 h. Representing the difference in heat output generated between the experimental and control cells versus time, the bacterial growth curves were obtained and the thermograms were compared using different concentrations of the metallic dissolution. This study highlights the role of zinc sulfate in suppressing bacteria growth at certain concentrations measured by microcalorimetric techniques. Such thermodynamic technique evidences the potential use of metallic dissolution in the medical industry, among others, in order to take advantage of its bactericide property.