387
therapeutics, genetically engineered microbes such as Lactobacillus with genes for
antiviral compounds are inserted (Hibberd and Davidson 2008).
16.4 Mechanism of Action
Several mechanisms about the mode of action of probiotics for therapeutic effects
have been postulated. Various in vivo studies and probiotic clinical trials suggested
beneficial effects for the relief of many disorders such as irritable bowel syndrome.
The mechanism of action of probiotic organisms could be derived from their stimulation of phagocytosis, production of antimicrobial compounds, resistance to colonization, antimutagenic effects, cytokine production, and effects on enzyme activity
and enzyme delivery (Vemuri et al. 2014).
Microbes ferment carbohydrates (saccharolytic fermentation) for the source of
energy, which help in food production. Many microbes metabolize carbohydrates
and dietary fiber, including nonabsorbed sugars, polysaccharides, and polyols. The
genera Bacteroides, Bifidobacterium, Eubacterium, Lactobacillus, and
Ruminococcus in the colon ferment carbohydrates. This fermentation results in the
production of the short-chain fatty acids and lactic acid together with gases such as
CO 2 , hydrogen, and methane, which regulate the microbiota. Increase in the presence of fermentable substrates in the gut results in flatulence and intestinal discomfort. Proteins can be metabolized by Clostridia and Peptococcus species, which are
utilized for nitrogen and produce branched-chain fatty acids along with many
nitrogenous compounds. Metabolites such as polyphenols and isoflavones may also
produce readily absorbable components such as equol after digestion. High stool
bulk results in shorter gut transit time and low risk of bowel discomfort and bowel
cancer. Bacterial mass causes fermentation of dietary fibers and contributes significantly to the stool bulk. Intestinal microbiota produce microbial antigens that have
an important role in disease resistance and the maturation of lymphoid tissue in the
gut (Hardy et al. 2013).
Probiotics have protective functions by modulation of immune activity and epithelial function in the intestine by regulation of the nuclear factor-κB pathway or
alteration in signal transduction pathways. Inhibition of tumor necrosis factor and
occlusion in the epithelial tight junctions leads to prevention of cytokine-induced
apoptosis (Vemuri et al. 2014).
16.5 Common Gut Flora
At the time of birth, the GI tract is sterile and the immune system is simple and natural. In the postnatal period a new microflora is formed in the human gut with an
additional source from the mother’s milk. Common bacteria in mother’s milk
include streptococci, Corynebacterium, lactobacilli, micrococci, and
Bifidobacterium, which may originate from the nipple or from the milk ducts.
Human breast milk is a relevant source of lactobacilli for newborns (Castellazzi
16 Probiotics
therapeutics, genetically engineered microbes such as Lactobacillus with genes for
antiviral compounds are inserted (Hibberd and Davidson 2008).
16.4 Mechanism of Action
Several mechanisms about the mode of action of probiotics for therapeutic effects
have been postulated. Various in vivo studies and probiotic clinical trials suggested
beneficial effects for the relief of many disorders such as irritable bowel syndrome.
The mechanism of action of probiotic organisms could be derived from their stimulation of phagocytosis, production of antimicrobial compounds, resistance to colonization, antimutagenic effects, cytokine production, and effects on enzyme activity
and enzyme delivery (Vemuri et al. 2014).
Microbes ferment carbohydrates (saccharolytic fermentation) for the source of
energy, which help in food production. Many microbes metabolize carbohydrates
and dietary fiber, including nonabsorbed sugars, polysaccharides, and polyols. The
genera Bacteroides, Bifidobacterium, Eubacterium, Lactobacillus, and
Ruminococcus in the colon ferment carbohydrates. This fermentation results in the
production of the short-chain fatty acids and lactic acid together with gases such as
CO 2 , hydrogen, and methane, which regulate the microbiota. Increase in the presence of fermentable substrates in the gut results in flatulence and intestinal discomfort. Proteins can be metabolized by Clostridia and Peptococcus species, which are
utilized for nitrogen and produce branched-chain fatty acids along with many
nitrogenous compounds. Metabolites such as polyphenols and isoflavones may also
produce readily absorbable components such as equol after digestion. High stool
bulk results in shorter gut transit time and low risk of bowel discomfort and bowel
cancer. Bacterial mass causes fermentation of dietary fibers and contributes significantly to the stool bulk. Intestinal microbiota produce microbial antigens that have
an important role in disease resistance and the maturation of lymphoid tissue in the
gut (Hardy et al. 2013).
Probiotics have protective functions by modulation of immune activity and epithelial function in the intestine by regulation of the nuclear factor-κB pathway or
alteration in signal transduction pathways. Inhibition of tumor necrosis factor and
occlusion in the epithelial tight junctions leads to prevention of cytokine-induced
apoptosis (Vemuri et al. 2014).
16.5 Common Gut Flora
At the time of birth, the GI tract is sterile and the immune system is simple and natural. In the postnatal period a new microflora is formed in the human gut with an
additional source from the mother’s milk. Common bacteria in mother’s milk
include streptococci, Corynebacterium, lactobacilli, micrococci, and
Bifidobacterium, which may originate from the nipple or from the milk ducts.
Human breast milk is a relevant source of lactobacilli for newborns (Castellazzi
16 Probiotics