The Significance of Inoculum Standardization and Cell Density on the Cr(VI) Bioremediation by Environmental Yeast Isolates

FERNÁNDEZ P,; FARIÑA J.I,; CASTELLANOS DE FIGUEROA, LUCÍA INÉS

WATER AIR AND SOIL POLLUTION

SPRINGER

Lugar: London; Año: 2010 vol. 206 p. 275 - 279

0049-6979

Abstract: The influence of inoculum preparation and cell density on the efficiency of Cr(VI)bioremediation was assessed with two chromate-resistant yeasts, Pichia jadinii M9 and Pichia anomala M10, isolated from textile wastewaters. Batch cultures in YNB´ liquid medium (YNB w/o amino acids and ammonium sulfate plus sucrose and ammonium sulfate) containing 1 mM initial Cr(VI) concentrations revealed that heavy metal removal in both isolates was substantially affected by the inoculation procedure. Inocula with high initial density or pre-grown in a nutritionally rich medium (Malt Czapek) were found to be key factors in order to achieve successful Cr(VI) decontamination. In contrast, low-density inocula and/or synthetic media-precultured cells were shown to negativly influence Cr(VI) bioremediation, either by increasing the time for complete degradation or by reducing the percentage of heavy metal removed. These results emphasized the relevance of the selection of an appropriate inoculum culture medium and the possitive influence of increasing one order of magnitude inoculum cell density in order to achieve successful and rapid Cr(VI) removal. Under these considerations, the selected yeasts, P. jadinii M9 and P. anomala M10, exhibited a remarkable ability to tolerate and completely reduce Cr(VI) concentrations up to 1 mM, thus being candidates for potential applications in bioremediation of Cr(VI)-contaminated environments.