الفهرس 
Heavy metals and their occurrence in the environmentOnly 14 pages are availabe for public view
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Abstract
Heavy metals differ from other toxic substances in that they
are neither created nor destroyed by humans. Lead and cadmium
are now recognized to be two of most important heavy metal
contaminants in the environment. They released into the
environment from natural and anthropogenic sources
contaminating food and water. Chronic oral ingestion of cadmium
and lead is associated with adverse effects in the skin, internal
organs and nervous system. It was reported that lead and cadmium
poisoning causes renal dysfunction, liver cirrhosis, damage to the
central nervous system, anemia and impaired the osteoclasts
function as well bone resorption.
Lactic acid bacteria (LAB) are widely used for the production
of fermented foods and are also part of the intestinal microflora.
Numerous investigations indicated that LAB have beneficial health
effects in humans Among these are: improved nutritional value of
food, control of intestinal infections, improved digestion of lactose,
control of some types of cancer, and control of serum cholesterol
levels. Some potential benefits may result from growth and action
of the bacteria during the manufacture of cultured foods. One of
the effects identified is the protection against toxins contained in
foods such as heterocyclic aromatic amines, polycyclic aromatic
hydrocarbons, mycotoxins and reactive oxygen species.
The reported metal removal by different inactivated
biomasses, and the toxin removal capacity of lactic acid bacteria in
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Summary
vitro, inspired us to assess the ability of lactic acid bacteria to
remove or reduce the toxicity of cadmium, and lead in vivo.
Therefore this study was conducted to investigate the effect of
lactic acid bacteria on the toxicity induced by lead and cadmium in
rats. Forty two of Albino rats (Sprague Dowely strain) male of an
average weight 130 ± 10 g were purchased from animal house of
National Research Center. The experiment was carried out in the
experimental animal house of NRC for 6 weeks and the animals
were divided into 6 groups each group contains 7 rats:
Group1 (G1): fed on basal diet (Negative Control); Group2 (G2):
fed on fed on contaminated diet with 0.025mg lead acetate/kg diet
+ 0.025mg cadmium chloride/kg diet (Positive Control); Group3
(G3): fed on basal diet + strain 1 of lactic acid bacteria
(Streptococcus thermophilus); Group4 (G4): fed on basal diet +
strain 2 of lactic acid bacteria (Lactobacillus bulgaricus); Group5
(G5): fed on contaminated diet with (0.025mg lead acetate/kg diet
+0.025mg cadmium chloride/kg diet) + strain1 (Streptococcus
thermophilas) and Group6 (G6): fed on contaminated diet with
(0.025mg lead acetate /kg diet + 0.025mg cadmium chloride/kg
diet) + strain 2 (Lactobacillus bulgaricus).
The obtained results could be summarized in the following:-
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Summary
1- Effect of lactic acid bacteria on biological evaluation
a) The group received lactic acid bacteria strain1 and strain2
supplemented to basal diet showed that body weight gain (BWG),
food intake (FI) and feed efficiency ratio (FER) values were
around negative control (basal diet).
b) The group received contaminated diet with lead and cadmium
mixture showed that BWG, FI and FER values were very
significantly lower as compared to negative control.
c) The group received lactic acid bacteria strain1 (Streptococcus
thermophilas) and lactic acid bacteria strain 2 (Lactobacillus
bulgaricus) supplemented to contaminated diet with lead and
cadmium showed significant improved in BWG, FI & FER values
as compared to positive control.
2-Effect of lactic acid bacteria on kidney functions:-
a) The group received lactic acid bacteria strain1 and strain2
supplemented to basal diet showed that urea and creatinine values
were around negative control (basal diet), it is clear that no bad
effect for lactic acid bacteria on kidney function
b) The group received contaminated diet with lead and cadmium
mixture showed that urea and creatinine values were very
significantly higher as compared to negative control. This result
indicated on the toxicity of lead and cadmium on kidney functions.
c)The group received lactic acid bacteria strain1 (Streptococcus
thermophilas) and lactic acid bacteria strain 2 (Lactobacillus
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Summary
bulgaricus) supplemented to contaminated diet with lead and
cadmium showed significant improved in urea and creatinine
levels as compared to positive control, it is clear that lactic acid
bacteria have the ability to remove lead and cadmium toxicity.
3-Effect of lactic acid bacteria on liver functions:-
a) The group received lactic acid bacteria strain1 and strain2
supplemented to basal diet showed that AST and ALT values were
around negative control (basal diet), it is clear that no bad effect for
lactic acid bacteria on liver functions.
b) The group received contaminated diet with lead and cadmium
mixture showed that AST and ALT values were very significantly
higher as compared to negative control. This result indicated on the
toxicity of lead and cadmium on liver functions.
c) The group received lactic acid bacteria strain1 (Streptococcus
thermophilas) and lactic acid bacteria strain 2 (Lactobacillus
bulgaricus) supplemented to contaminated diet with lead and
cadmium showed significant improved in AST and ALT levels as
compared to positive control, it is obvious that lactic acid bacteria
have the ability to remove lead and cadmium toxicity.
4-Effect of lactic acid bacteria on glutathione peroxydase
(GPX)
a) The group received lactic acid bacteria strain1 and strain2
supplemented to basal diet showed that glutathione peroxydase
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Summary
(GPX) values were around negative control (basal diet), it is clear
that no bad effect for lactic acid bacteria on (GPX).
b) The results illustrated that heavy metals treatment very
significant depleted GPX activity as compared to negative control
(p<0.05). This result indicated on the toxicity of lead and cadmium
on liver.
c) The decreased in GPX due to Pb and Cd treatment was
significantly reduced (p≤0.05) when diet supplemented with
strain1 (Streptococcus thermophilas) and (Lactobacillus
bulgaricus), the former strain was better than the later.
5- Effect of lactic acid bacteria on Blood hemoglobin
a) The group received lactic acid bacteria strain1 and strain2
supplemented to basal diet showed that blood hemoglobin levels
were around negative control (basal diet), it is clear that no bad
effect for lactic acid bacteria on blood hemoglobin.
b) The group received contaminated diet with lead and cadmium
mixture showed that hemoglobin levels were very significantly
lower as compared to negative control. This result indicated on
anemia caused by lead and cadmium mixture.
c) The decreased in blood hemoglobin was very significantly
improved (p<0.05) by strain1 (Streptococcus thermophilas) and
strain2 (Lactobacillus bulgaricus) supplemented to lead and
cadmium mixture treated group.
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Summary
6- Effect of lactic acid bacteria on lead and cadmium levels in
blood of rats after exposure to Pb and Cd mixture
a) Groups received lactic acid bacteria strain 1 and strain 2
supplemented to basal diet gave concentrations around negative
control.
b) The group received contaminated diet with lead and cadmium
showed high significant increased in positive control as compared
to negative control (p< 0.05) in levels of lead and cadmium in
blood of rats .
c) There was significantly lower (p< 0.05) in the groups received
lead and cadmium plus lactic acid bacteria strain1 (Streptococcus
thermophilas) and strain2 (Lactobacillus bulgaricus) as compared
to positive control. It is clear that lactic acid bacteria have the
ability to remove lead and cadmium in experimental animals.
7-Effect of Lactic acid bacteria on organs weight (g)
a) Groups received lactic acid bacteria strain 1 and strain 2
supplemented to basal diet gave organs weight (heart, kidney, liver,
spleen, brain) around negative control.
b) Group received contaminated diet with Pb and Cd mixture showed
very significantly increased in different organs weight (p<0.05) as
compared to negative group.
c) Group received strain1 (Streptococcus thermophilas) and strain2
(Lactobacillus bulgaricus) supplemented to contaminated diet
significantly lower the increased in different organs weight different
organs weight caused by positive control.