الفهرس 
Initial Concentration of metals ions.
Materials and MethodsOnly 14 pages are availabe for public view
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Abstract
In this study, screening among different yeast strains to choose the
suitable strain for enrichment with iron and zinc, when used as a feed
supplement, could represent a new and safer solution for improvement
the iron and zinc amount in human.
The current study could be summarized in the following three main
chapters.
The first chapter:
Introduction: contains a general introduction about biosorption
technology consists of the ability of the biological materials to bind and
concentrate heavy metals ion through metabolically mediated or physicochemical
pathways. Important of iron and zinc in human and its roles,
which deficiency are serious public health problems throughout the life
cycle in both industrialized and developing countries. In this manner, the
enriched yeast with iron and zinc ions is found to be a better absorbability
in the organism and it is safe. In addition, yeast biomass is a good source
of proteins, essential amino acids and vitamins. As well as, the factors
affecting the yeast enrichment were also reported.
The second chapter:
Experiment: represents the experiment part of the study which
shows the determination of the absorption efficiency (%) of yeast strains
for iron and zinc ions. screening of six yeast strains was utilized to
investigate such process in the composition of growth medium. Different
parameters, such as pH, contact time, different source of ions, initial
concentration of ions and interference between iron and zinc ions in
growth medium were affected on the biosorption process.
II
The third chapter:
Results and Discussion: is devoted to represent the results and
interpretation the discussion of these results. This chapter revealed the
following remarks:-
1- The results demonstrate that yeast strains Y-64 and Y-66 are
higher Fe ions (100 ppm) and zinc ions (30 ppm) absorption
(ppm), absorption efficiency (%) and yeast cell biomass (g/L) for
both metal ions, compared with other strains after cultivation time
48 hr. These two yeast strains have a certain enrichment ability for
iron more than the other yeast strains tested.
2- The effect of kinds of salt, initial concentration metal ions,
cultivation time, pH, competitive absorption of two metals,
fermenting dough power and bread making by using enriched
yeasts were tested. The absorption efficiency of yeast cell strains
Y-64 and Y-66 after 24 and 48 hrs. cultivation for differences iron
and zinc forms (sulphate, nitrate and chloride) were determined.
The absorption efficiency increased with increasing the metal ions
concentration from 25-100 (ppm) in the three tested iron and zinc
ions for two yeast strains. The results indicate that the Fe and Zn
content reached a maximum absorption only when ferrous and
zinc sulfate were used as the source of Fe and Zn. It was, also
noticed that strains Y-66 had a high absorption efficiency in
absorption than strain Y-64 and little change in biomass at
different (24 – 48 hrs.) cultivation time.
3- Contact times applied in this study were 0.15, 0.30, 1, 2, 3, 6, 12,
24 and 48 hrs. Absorption (ppm) and yield of yeast (g/L) increased
as the contact time increased and the absorption of iron and zinc
III
on yeast was rapid for the first 3 hr and seemed to be stable after 6
hrs. The high absorption efficiency (%) of iron and zinc