Probiotics are living microorganisms that provide health benefits when consumed in adequate amounts. They include lactic acid bacteria like Lactobacillus and Bifidobacterium species. Probiotics can survive the harsh conditions of the gastrointestinal tract, adhere to intestinal cells, produce antimicrobial substances, and modulate the immune system to help crowd out pathogenic bacteria. While generally safe, some risks include mild digestive side effects, infection in immunocompromised individuals, and potential transfer of antibiotic resistance genes. More research is still needed to substantiate health claims and develop targeted "designer" probiotic strains.

2. Probiotics are living microorganisms that, administered in adequate
amounts, confer a healthy benefits to host
(Ayeni et al 2011, Gupta and Garg 2009).
Probiotics are one of the functional food that link diet and food.
These are
• Live micro organisms
• Can affect the intestinal flora
• Promoted as food supplements
• Huge market potential
• Many health claims…
Probiotics

3. Microorganism as Probiotics
• Lactic acid bacteria (LAB) (Sonal et al 2008)
• Lactobacillus species & Bifidobacterium species
(Ayeni et al 2011, Yateem et al. 2008)
• Bacillus cereus & Propionibacterium (less potential)
(Mahasneh & Abbas 2010, Saraf et al 2010)
• Non pathogenic Escherichia coli (Sonal et al 2008)
• Saccharomyces cerevisiae (Kurugol & Koturoglu 2005)
• Enterococcus faecalis ( Tatiane FA and Célia L de L)
• Aspergillus oryzae (Parvez et al 2006)

4. Ellie Metchnikoff, the first scientist who proposed the therapeutic use of lactic acid bacteria.
•Lactic acid bacteria were first discovered by Pasteur in 1857
•Their isolation from rancid milk was reported in 1878 by Lister.
• In 1889 Tissier discovered Bifidobacterium spp.
The first stable cultures of Lactobacillus casei
strain Shirota were made in 1930 by Dr. Minoru
Shirota

5. Functional Properties of Probiotics
The Probiotic bacteria should overcome the many barriers of the host body.
• In oral cavity enzymes such as lysozyme and extremely low pH of
stomach (1.5).
• In small and large intestine bile and pancreatic juices has overcomed by
probiotics.
• Probiotics has able to tolerate the bile salt in the GIT to function properly.
• Ten strain of LAB has isolated from naturally fermented shrimps, show
more survival rate 50% than simulated gastric juices and four of them
showed a survival rate more than 50% in simulated intestinal juices.
• Bifidobacterium longum showed great variations to GIT juices, but none of
them has ability after exposure to gastric juices at pH 1.5.

7. Cholesterol Reduction
Some lactobacillus species such as L. acidophilus could reduce total
cholesterol and low density lipo-proteins (LDL) cholesterol.
In Vitro number of cholesterol-lowering mechanism has been studied
• Cholesterol assimilation by Probiotics.
(Morgolles et al 2003)
• Enzymatic de-conjugation of bile salts by bile salt hydrolyses.
(Zheng et al 2010)
• Incorporation of cholesterol into membrane of cells is not excluded
and finally binding of cholesterol to bacterial cell wall.
(Liong and Shah 2005)

8. Mechanism of cholesterol assimilation by Probiotics
Direct Indirect
Inhibiting the de
novo synthesis of
cholesterol
Decreasing the
intestinal absorption of
dietary cholesterol
Lactose,
calcium hydroxyl
methyl glutarate,
uric acid,
whey proteins
Assimilation Binding Degradation
Deconjugating the cholesterol
to bile salts
Cholesterol assimilation

9. Antimicrobial Activity
• Produce a wide range of antimicrobial substances
hydrogen peroxide
organic acids
Bacteriocin
acidophilin
• Produce vitamins (especially Vitamin B and vitamin K)
• Act as barriers to prevent harmful bacteria from colonizing
the intestines

10. Bacteriocins are proteinaceous toxins (has bacteriostatic and
bacteriocidal effect) produced by bacteria to inhibit the growth of
similar or closely related bacterial strain.
Bacteriocins of LAB are arranged into four classes
• Class I bacteriocins are lantibiotics, are small peptides that contains
post transitionally modified amino acids residues such as lanthionine.
• Class ll bacteriocins are small, heat stable, nonlanthionine-containing
peptides.
• Class lll bacteriocins are large, heat labile, nonlantibiotics.
• Class IV bacteriocins are complex bacteriocins chemical moieties
such as lipid and carbohydrates.
Contin…..

11. Nisin
• A lantibiotic, produced by different Lactococcuc lactis spp is a most studied
bacteriocin.
• L. acidophilus produces acidophilin, lactocidin and acidolin. They have
demonstrated an in vitro inhibitory activity against Bacillus, Klebsiella,
Pseudomonas, Proteus, Salmonella, Shigella, Staphylococcus and Vibrio
spp and enteropathogenic E.Coli.
• L. lactis spp is produced Nisin, have been isolated from human milk during
early lactation period and its antagonistics activity was determined against
Micrococcus leuteus.

12. Adherence to Intestinal epithelial cells
• To prevent the intestinal epithelium from pathogenic bacterial
invasion by Lactobacillus strains, they should resist biological
barriers such as gastric acid and bile salts, then they should adhere
to the host intestinal epithelium (Tsai et al 2005).
• The role of exopolysaccharides and the involvement of lipotechoic
acid in the adherence of lactobacillus and geneital epithelia has been
reported (Boris et al.1998).
• In-Vitro B. longum possessed high adherent activity to Caco-2 cell
monolayers and suppressed the adherence of P. aeruginosa to the
monolayers (Matsumoto et al 2008).
• Lactobacillus strains from animal origins were able to adhere
strongly to human Int-407 and Caco-2 epithelial cells in addition to
poultry and swine intestinal epithelium to columnar epithelial cells
isolated from the BALB/c mouse intestine (Tsai & coworkers 2011).

13. Mechanism of action of Probiotics
• Probiotics has mechanism of action including enhancement of epithelial barrier
integrity by increasing the secretion of mucus and by triggering inflammation in
enterocytes of the intestine.
• Chaichlowski and coworkers(2007) found an increase in number of goblet cells on
chicken intestinal villi as response to probiotics L casei, L acidophilus,
Bifidobacterium and E faecalis mixture treatment and suggested that metabolites
produced during bacterial fermentation may play role in growth and maturation of
goblet cells.
• Several Lactobacillus species increased mucin expression in the human intestinal
cell lines Caco-2 (MUC2) and HT29 (MUC2 and MUC3), thus blocking pathogenic
E.coli invasion and adherence.
• Probiotic has competition with potential pathogens for nutrients and energy source,
thus prevent such pathogens from growth and proliferation in gut.
• Production of antimicrobial substances by probiotics have been reported to inhibit
the growth of pathogenic bacteria such as antimicrobial effect of Lactobacillus spp
on Helicobactor pylori infection of gastric mucosa.

14. • Auto-inducers are chemical signaling molecules that allow bacteria
to communicate with each other and with the surrounding
environment a phenomena called Quorum sensing (Vila et al 2010).
• Probiotics has the ability to modulate the immune system against
pathogens via antibody production and activation of lymphocytes
(Ng et al 2009).
• Lactobacillus and Bifidobacterium probiotics induced macrophages
to express more nitric oxide and inflammatory cytokines to increase
antiviral activity (O Hara et al 2006).
Contin…

16. Safety of Probiotics
• Probiotics has side effects, would probably be mild digestive
disturbances including gas and bloating (Mahasneh and Abbas 2010).
• Due to Lactobacillus spp Some local or systemic infection has
occurred Including septicemia and endocarditis (Boyle et al 2006).
• Many cases of fungemia have been reported in humans treated with
the probiotic S. boulardii (Hannequin et al 2000).
• Unhealthy metabolic activities of probiotics such as intestinal mucus
layer degradation in which the accumulation of probiotics along the
GIT might cause gastrointestinal disturbances including intestinal
inflammation (Soccol et al 2010, Ooi and Liong 2010).
• Probiotics some time cause too much stimulation of immune system
(Boyle et al. 2006).

17. Possible risk of using probiotics is transferring antibiotic resistance
genes between microorganism esp. more pathogenic bacteria in the
intestinal microbiota. e.g. L. returi and L. plantarum have been found
to carry antibiotic resistance genes (Yan & Polk 2011).
Vancomycin resistant genes of many Lactobacillus strains are
chromosomally encoded and not inducible or transferable, which would
increase the safety level of probiotic use
(Marteau 2001, Boyle et al 2006).
Contin….

18. • Probiotics have ability to promote wide variety of desired physiological effects
for better human health.
• Traditional fermented food are among the most promising sources for the
isolation of unique probiotic bacteria esp. Lactic acid group.
• The candidate probiotic microorganism must approved international criterion
include resistance to low pH, gastric and intestinal enzyme and bile toxicity.
• The ability to adhere to epithelial cells and antimicrobial substances is also a
important as the safety concerns.
• To substantiate the role of probiotics in disease therapy more in vivo studies are
needed and further more the need for specific designer probiotics should be
thoroughly investigated and developed.
Conclusion