ANBI 470.3 Lecture Notes - Lecture 6: Pattern Recognition Receptor, Bacteriocin, Probiotic
20 Jun 2018
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Mechanisms of action:
- Competitive Exclusion: space
oAdhesion to epithelium is necessary for pathogens to become established and
cause infection
oPreoccupation of sites by probiotics prevent pathogens attachment
oorganism attach to the mucus membrane, mucus or epithelial cells. they have
receptors that allow attachment. if a probiotic is attaching to them instead of
pathogens then the receptors are covered then the pathogen cannot bind to
them
- Competitive exclusion: nutrients
oProbiotics utilize available nutrients competing with pathogens
All microorganism require iron for growth except lactobacilli, lactobacilli
can suck it up and take it away from pathogens?
obacteria need specific nutrients present in their environment if a probiotic bind
to them or uses them first then it does not allow pathogenic thing to grow
- Aggregation
oProbiotic microorganisms may coat pathogens preventing their attachment and
facilitating removal by peristalsis
oCoaggregate: more than one probiotic bacterial species could be involved
- Anti-microbial effects
oMany species produce antibiotic compounds
For example bacteriocins are secreted proteins which may limit growth of
competitive bacteria (have effects on both gram negative and positive)
oSome bacteria deconjugate bile acids which are bacteriostatic and this also could
decrease the cholesterol level
oorganisms in complex communities are constantly fight for space and nutrients
can see production of bacteriocins which can damage other cells near it
can punch wholes in the membranes of other bacteria
oorganic acids are bacteriostatic particularly against some gram negative bacteria
some organic acids may also reduce virulence gene expression in some
pathogens
often associated with probiotic ability to change community composition
and thus relative amount of organic acids
oothers:
hydrogen peroxide
nitric oxide
these have oxidative damage capabilities
- Immune stimulation
oSpecialized receptors called pattern recognition receptors bind bacteria
components
Activate immune cells and enhance immune response
Activate” innate” immune mechanisms
Increase mucin secretion by goblet cells
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Document Summary
Competitive exclusion: nutrients: probiotics utilize available nutrients competing with pathogens. Aggregation: probiotic microorganisms may coat pathogens preventing their attachment and facilitating removal by peristalsis, coaggregate: more than one probiotic bacterial species could be involved. Anti-microbial effects: many species produce antibiotic compounds. Often associated with probiotic ability to change community composition and thus relative amount of organic acids: others: Nitric oxide these have oxidative damage capabilities. Immune stimulation: specialized receptors called pattern recognition receptors bind bacteria components. Activate immune cells and enhance immune response. Probiotics can decrease epithelial permeability: non pathogens are present in the gut lumens producing compounds as well that can effect your immune system too its not just pathogens in there. Probiotic bacteria increase other bacterial species which then exclude the pathogen. Many possible mechanisms but for most no specific information. With undefined mechanisms conditions under which product will be successful are. Complex and dynamic gut microbiota difficult to study unknown.
