Effect of mercury and organomercurials on cellular glucose utilization: a study using resting mercury-resistant yeast cells

Abstract

Mercury compounds are highly toxic to all types of living cells. Isolated yeast strains of Rhodotorula rubra showed high and low resistance pattern towards mercury and organomercurial compounds. To investigate the basis of differential sensitivity of these two types of strains, glucose utilization was measured in the presence of mercury compounds. Glucose utilization process remained unaffected in resting cells of highly Hg(2+)-resistant strain in the presence of HgCl(2) but not in the presence of phenylmercuric acetate and thimerosal. However, HgCl(2) significantly affected glucose utilization in the case of low-resistant cells. The Hg-retaining ability of the cell wall of highly Hg(2+)-resistant yeast strain was greater than that of the weakly Hg(2+)-resistant strain. The spheroplast-bound Hg(2+) was also significantly less in the highly Hg(2+)-resistant strain than in the weakly Hg(2+)-resistant strain. Glucose uptake machinery was not affected in the presence of toxic metal ions in the case of high-resistant strains. But in the case of low Hg(2+)-resistant strain, glucose transport system may be affected either by inactivation of sensor proteins containing -SH group associated with glucose uptake. Cell wall of mercury-resistant yeast cells may play an important role in heavy metal bioremediation process.