Probiotic Spore Formers Enhances Host Health- Juniper Publishers
Juniper Publishers- Journal of Cell Science
Abstract
Wild species of spore formers from various sources
has remarkable probiotic potential. Many of the isolates possess
non-hemolysis, non-lecithin’s activity, acid and bile tolerance,
resistance to artificial gastric and intestinal fluids and antagonistic
action towards pathogens. Most of the spores and vegetative cells of
isolates showed excellent resistance to acid and bile. Many of the wild
species of sporeformers are able to produce siderophores, and
antimicrobial substances. Adhesive rate of sporeformers were found to be
more than vegetative cells on intestinal mucous. Both spores and
vegetative cells were auto aggregating but auto aggregation of
vegetative cells was found to be more than that of spores. Vegetative
cells of isolates coaggregated pathogens while spores remained to be
nonaggregating. In vivo Immunomodulatory studies also proved that the
sporeformers has a significant role in improving both humoral and cell
mediated immunity. Ingestion of probiotic spores is very significant
because they can survive in the harsh gastrointestinal conditions which
further form vegetative cells during favorable situations.
Keywords: Probiotic; Sporeformers; Antagonism; Cell surface property; Gut immunity
Introduction
The concept of probiotics has a long history of
health claims. For example, in a Persian version of the Old Testament
(Genesis 18:8), it states “Abraham owed his longevity to the consumption
of sour milk. Replacing in-feed antibiotics with non-antibiotic
alternatives is, therefore, an ever-increasing necessity. However, the
withdrawal of all growth promoting factors is not a simple matter since
this will not only affect feed efficiency but will also increase the
mortality and morbidity of animals [1]. Sporeformers are capable of
growth and metabolic activity only when in the vegetative state, and
resort to sporulation when conditions of inadequate nutrition or other
challenge to survival is experienced [2]. Currently, there is no
universalclass of probiotic bacterium although the most common types
available are lactic acid bacteria (e.g., Lactobacillus spp.). These
bacteria are found normally in the gastrointestinal tract (GIT) of
humans and animals and there is the vague notion that the use of
indigenous or commensal microorganisms is somehow restoring the natural
microflora to the gut. A second class comprises those that are not
normally found in the GIT. For example, Saccharomyces boulardii has been
shown to be effective in preventing the recurrence of Clostridium
difficile-induced pseudo membranous colitis [3] as well as the
antagonistic action of Escherichia coli [4]. S. boulardii products are
currently being marketed for human use. Within this group of
allochthonous probiotic microbes are the spore-forming bacteria,
normally members of the genus Bacillus. Here, the product is used in the
spore form and thus can be stored indefinitely on the shelf. The use of
spore-based products raises
a number of questions though. Since the bacterial species being used are
not considered resident members of the gastrointestinal microflora how
do they exert a beneficial effect? Because the natural life cycle of
Initial efforts to document a physiological impact of probiotic bacteria
often focus on the following three criteria:
a) inherent characteristics of strains that would enable intestinal tract survival
b) the fate of the fed bacterium, and
c) the impact of consumption of the live bacterium on intestinal flora.
It should be noted, however, that effects beyond an
impact on intestinal flora, and at extra intestinal sites, have been
documented for many probiotic strains [4]. A few such studies have been
done with sporeformers. Hydrophobicity, auto aggregation and mucin
adhesion are important attributes which help in the attachment to
various substrata that explain the probiotic nature of the microorganism
[5].
The Gut as A Habitat for Sporeformers
Since spores of Bacillus species can readily be found
in the soil, one might assume that the live (vegetative) bacteria that
produced these spores are also soil inhabitants. This, however, is
proving an unfounded assumption and, of course, the ability of spores to
be dispersed in dust and water means that spores can be found almost
everywhere. So, where they are found does
not indicate their natural habitat. Bacillus spore-forming species
are commonly found in the gut of animals and insects and
experimentally this is often demonstrated by faecal sampling
[6]. The presence of Bacillus species, whether as spores or
vegetative cells, within the gut could arise from ingestion of
bacteria associated with soil endosymbiotic relationship with
their host, being able temporarily to survive and proliferate
within the gastrointestinal tract (GIT). In some cases, though,
the endosymbiont has evolved further into a pathogen,
exploiting the gut as its primary portal of entry to the host (B.
anthracis) oras the site for synthesis of enterotoxins (B. cereus,
B. thuringiensis) [7].
Antagonistic Mechanism of Sporeformers
There are different mechanisms by which probiotic can
exert inhibition towards pathogens. Production of bacteriocin
and cell surface properties are the two major way to eliminate
pathogens. Enteric pathogens are of great importance because
they cause infections both in man and animals. A comparative
study of two sporeformers Bacillus coagulans and Bacillus
clausii found to produce inhibitory substances against
Salmonella typhi, Bacillus subtilis and Klebsiella. [6]. find out
the inhibitory effect of Bacillus sporeformers against enteric
fever pathogen [8]. Comparative studies on the adhesion and
cell surface properties of sporeformers and enteric pathogens
are scarce in the field of probiotic research. Hydrophobicity,
auto aggregation and mucin adhesion are important attributes
which help in the attachment to various substrata that explain
the probiotic nature of the microorganism [5]. Sporeforming
isolates, possessed basic probiotic qualities and cell surface
properties which enable them to fight against enteric pathogens
[8]. found that through adhesion ability and colonization on [9]
tissues, probiotic microorganisms can prevent pathogen access
by steric interactions or specific blockage on cell receptors.
An experimental study of [10] reveals that both spore and
vegetative phases of isolates possess a different rate of adhesion
potentials, which indicates that cell surface properties were
involved in adhesion process. Compared to spores, vegetative
cells of selected isolates remains to be less adhesive on intestinal
mucous. This study also reveals that increased adhesion of
the spore phase of the isolates, on intestinal mucin than their
corresponding vegetative cells may be due to their hydrophobic
nature. Spores adhered better than the corresponding
vegetative cells on mucin. Adherence of organisms to xylene,
a non-polar solvent, demonstrates hydrophobic nature of the
isolates. Increased hydrophobic nature of spores than their
corresponding vegetative cells may be due to presence of
hydrophobic proteins present in spore coat and found that cell
surface properties of bacteria, especially sporeformers play key
role in adhesion mechanism. Hydrophobic cell surface nature
of Bacillus coagulans and Bacillus clausii also reported by [6].
Doyle RJ [11] found that agents which disrupt protein structure
modified the hydrophobicity of spores, suggesting that the
spore coat also has hydrophobic sites. In vivo colonization, of
MBTU PBBM1 Bacillus subtilis spores establish the adhesion
ability and there by exert probiotic effects in gastrointestinal
tract (GIT). A stable colonization in gastrointestinal tract was
noticed in animals which received 108 spores of MBTU PBBM1
and this indicates that a particular dose is necessary for the
establishment of administered spores in the gastrointestinal
tract of mouse [12].
Immune Stimulation of Probiotic Sporeformers
A number of studies in humans and animal models have
provided strong evidence that oral administration of spores
stimulates the immune system. This tells us that spores are
neither innocuous gut passengers nor treated as a food. A
small proportion of spores have been shown to disseminate to
the primary lymphoid tissues of the GALT (Peye_s Patches and
mesenteric lymph nodes) following oral inoculation [13] and in
vitro studies have shown that phagocytosed spores can germinate
and express vegetative genes but are unable to replicate [14].
Following oral dosing, anti-spore IgG responses could be
detected at significant levels. Anti-spore IgG and secretory IgA
(sIgA) could be produced by a normal process of antigen uptake
by B cells. Detailed analysis of the subclasses showed IgG2a to
be the initial subclass produced and this is often seen as being
indicative of a type 1 (Th1) T-cell response [15]. Th1 responses
are important for IgG synthesis but more importantly for CTL
(cytotoxic T lymphocyte) recruitment and are important for
the destruction of intracellular microorganisms (e.g., viruses,
Salmonella spp.) and involve presentation of antigens on the
surface of the host cell by a class I MHC processing pathway.
Support for Th1 responses has been provided by the analysis of
cytokines in vivo that showed synthesis of IFN- and TNF in the
GALT and secondary lymphoid organs when spores of B. subtilis
or B. pumilus were administered to mice [14]. Serum Ig A and
Serum Ig G antibodies are implicated in host defense against
bacterial infections. Study conducted by [10] resulted MBTU
PBBM1 spores have capacity to stimulation of serum Ig A and
serum Ig G in treated groups in a dose dependent manner. This
means that spores can modulate humoral immune response.
Immunomodulation of Sporeforming Probiotics
Stimulation of the immune system, or immunomodulation,
is considered an important mechanism to support probiosis.
A few studies in humans and animal models have provided
strong evidence that oral administration of spores stimulates
the immune system. Large number of probiotic products in use
today are bacterial spore formers, mostly of the genus Bacillus
[16]. Stimulation of the immune system, or immunomodulation,
is considered an important mechanism to support probiosis. A
number of studies in humans and animal models have provided
strong evidence that oral administration of Bacillus spores
stimulates the immune system. Dose dependent studies [10]
revealed that group which receiving 1x108 spores showed an
effective humoral and cell mediated immune response in balb/c mice. So this dose can be decided as an appreciable measure
which can evoke a effective humoral and cell mediated immune
response. Studies also revealed that this strain could colonize
gastrointestinal tract which would further act as a key to the
initiation of immunomodulation. 30 days consumption of MBTU
PBBM1 spores had no adverse effects on animals’ general
health status, hematology, gut mucosal histology parameters.
The bacterial translocation was not observed [17,18]. Results
suggests that the ingestion of MBTU PBBM1 would enhance the
immunity indicating immunomodulatory effect.
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