Application of S. cerevisiae isolated from industrial effluent for zinc
biosorption and zinc-enriched SCP production
Abstract
Purpose: The aim of present study was to produce high quantity of
Zn-enriched yeast biomass in the presence of zinc metal, using S.
cerevisiae as an industrially important yeast strain. Methods: Yeast
isolates were obtained from two alcohol factories and S. cerevisiae
yeasts strains were identified using PCR method and DNA sequencing.
Then, growth rate of this yeast in present of Zn2+ as well as the level
of Zn2+ uptake by the yeast cells, were examined at 24-hour intervals
(0, 24, 48, and 72 h), using spectrophotometry and AAS method. qRT-PCR
technique was carried out to quantified expression level of Zrt1 and
Fet4 in yeast cells under these conditions. Also, the effect of pH of
culture medium on yeast growth rate, zinc absorbtion and Zrt1 and Fet4
expression level, was studied. After setting the optimum pH, Kjeldahl’s
method was applied for assessment of total protein content of yeast
cells. Results: In optimum conditions of 25 µg/ml of zinc in pH 6 and 24
h incubation, S. cerevisiae showed the maximum growth rate, zinc uptake
and expression level of Zrt1 and Fet4 as Zn transporters. Also, protein
content of S. cerevisiae biomass in these optimum conditions was above
50% (w/w). Discussion: we demonstrated that industrial effluents can be
used to produce Zn-enriched biomass however, further researches are
required.