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Microbes & Immunity Probiotics from ancient wisdom to modern days

A B 2.3. Mechanisms of probiotic action
As with many scientific endeavors, understanding is
deepened when considered in conjunction with the
mechanisms of action. 13,14 B. longum and L. plantarum
exert their health benefits through several mechanisms, 15,16
including:
Figure 2. Micrographs and details of the most commonly studied
probiotic strains, (A) Lactobacillus plantarum and (B) Bifidobacterium • Competition with pathogens: Both probiotics
11
longum 12 compete with harmful bacteria for nutrients and
adhesion sites, preventing the harmful bacteria from
Table 1. Typical morphological and microscopic colonizing the intestinal epithelium (gut wall). This is
characteristics of Lactobacillus plantarum and shown graphically in Figure 3, where a slug of lumen
Bifidobacterium longum is traced as it passes through the intestine. The clock
faces depicted here merely mark the passage of time
Probiotic strains L. plantarum B. longum (and not the time of day).
Magnification Typically×1,000 Typically ×~5000 • Inactivation of pathogenic toxins: Some strains can
Staining method Gram staining Nil staining neutralize toxins produced by pathogenic bacteria.
Cell shape Rod-shaped Rod-shaped with a • Production of beneficial substances: These probiotics
characteristic Y-shape or produce substances, such as lactic acid, that inhibit the
bifurcation growth of harmful bacteria.
Cell size 0.7 – 1.1 μm in 0.5 – 1.2 μm in diameter, • Enhancement of mucosal barrier: They interact with
diameter, 2 – 4 μm in 2 – 5 μm in length
length epithelial cells to strengthen the mucosal barrier,
Arrangement Single cells or short Single cells or short chains protecting against infections.
chains • Modulation of immune responses: These probiotics
can interact with immune cells, enhancing the body’s
immune response by stimulating the production of
• Common cold: Oral intake of L. plantarum with immune mediators, such as cytokines and secretory
another probiotic, Lactobacillus paracasei, has been immunoglobulin A. These help to protect the host
associated with improvements in common cold against infection. 17
symptoms. • Metabolic modulation: Some strains can influence
• High cholesterol: Oral intake of L. plantarum has metabolic processes, such as insulin resistance
been associated with modest reductions in cholesterol and cholesterol metabolism. They can ferment
levels. carbohydrates in the gut, resulting in the production
• Irritable bowel syndrome, a long-term disorder of the of short-chain fatty acids that promote gut health,
large intestine that causes stomach pain: Oral intake including butyrate, which has anti-inflammatory
of L. plantarum alone or with other probiotics has properties. 18
been associated with improvements in irritable bowel • Neurological effects: Emerging research suggests
syndrome. these probiotics may impact neurological signaling
• Infection of the airways: Oral intake of L. plantarum pathways. 19
alone or with other probiotics has been associated • Protection: These probiotics can exert their effects
with preventing airway infections in adults. through the production of antimicrobial substances,
• Ulcerative colitis, a type of inflammatory bowel such as bacteriocins, which inhibit the growth of
disease: Oral intake of L. plantarum, together with pathogenic bacteria. “Friendly” gut bacteria may
standard treatment, has been associated with increased eliminate pathogens by competing for energy
remission and prevention of relapse in people with resources. 20,21 In addition, these probiotic strains
ulcerative colitis. can modulate gut motility, further contributing to a
healthy gut environment.
2.2. WebMD overview of B. longum
Figure 4 graphically illustrates how probiotics occupy
According to WebMD, B. longum resides in the intestines the gut mucus lining, preventing harmful bacteria and their
and produces lactic and acetic acids, which aid in food toxins from gaining access. By competitively inhabiting
digestion, nutrient absorption, and defense against the mucosal area, a beneficial climate is created for other
potentially harmful microorganisms. beneficial bacteria to grow.

Volume 2 Issue 3 (2025) 33 doi: 10.36922/mi.6424