Antimicrobial activity of Lactobacillus.

Importance of Lactobacillus species in the context of antimicrobial therapies.

1. Antimicrobial activities of
Lactobacillus Species.

¡Hen by: Drug Phamacology Explained

2. Antimicrobial activities of
Lactobacillus.

3. Mechanisms of Antimicrobial Activity

1. Production of Lactic Acid:

» Acidification of the Environment:

Lactobacilli ferment sugars to produce lactic acid, lowering the pH of
their environment. This acidic condition inhibits the growth of many
harmful bacteria and fungi that cannot thrive in low pH environments.

» Inhibition of Pathogens:
The acidic environment directly disrupts the cell membranes of

pathogens, leading to their inactivation or death

4. duction of Bacteriocins:

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They have a narrow or broad spectrum of

- Bacteriocins: These are riboso
produced by Lactobacillus species.

Bacteriocins disrupt the integrih
lysis.

- Examples: Some weill-kno'
reuterin, which have shown effectiven:
*Listeria monocytogenes* and *Staphylococcus aureus”.

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against various pathogens like

bacteriocins include nisin

5. 3. Competition for Nutrients and Adhesion Sites

» Nutrient Competition: Lactobacillus species compete with pathogenic
microbes for essential nutrients, effectively starving the pathogens and
limiting their growth.

Adhesion to Surfaces: Lactobacilli can adhere to mucosal surfaces in
the human body, particularly in the gastrointestinal tract, thereby
preventing pathogens from colonizing these sites.

6. 4. Production of Hydrogen Peroxide:

» Oxidative Stress: Some Lactobacillus species produce
hydrogen peroxide (H202) as a byproduct of their
metabolism. This compound generates oxidative stress
in pathogenic microbes, damaging their cellular
components and inhibiting their growth.

7. 5. Modulation of Host Immune Responsemme

>» Immune System Stimulation:** Lactobacilli can modulate the host's
immune response by stimulating the production of
immunoglobulins (e.g., IgA) and other immune factors. This
enhanced immune response helps to combat invading pathogens

more effectively.

8. Applications

» Food Preservation: The antimicrobial properties of Lactobacillus are
harnessed in the production of fermented foods, where they help
preserve the product by inhibiting spoilage organisms and pathogens.

> Probiotics: Lactobacillus strains are used in probiotic supplements and
functional foods to promote gut heabith by maintaining a balanced
microbiota and protecting against gastrointestinal infections.

> Therapeutics: There is ongoing research into the use of Lactobacillus
strains as therapeutic agents to treat infections, especially in the
gastrointestinal and urogenital.

9. » Strain Specificity: The antimicrobial activity of Lactobacillus is
highly strain-specific, meaning that not all strains exhibit the
same level of effectiveness against pathogens.

>» Resistance Development: There is a potential concern that
pathogens could develop resistance to the antimicrobial
compounds produced by Lactobacillus, though this is less
common compared to antibiotics.

» Regulatory and Safety Issues: The use of live bacteria in food
and supplements must be carefully regulated to ensure safety
and efficacy, particularly in immunocompromised individuals.