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Probiotics, especially the ones from bacillus genus, are becoming popular solutions for nutritionists, first because we need to find alternative to antibiotics to control gut flora but as well because modern science enables us to understand better the mode of actions of beneficial bacteria and how to select them. The world of bacteria is indeed very wide and heterogeneous. All bacteria from the Bacillus species share 82% genes but the remaining 18% will vary between each strain. That is the same genetic variation that you will find between ourselves and cows.

Therefore, when we are selecting a probiotic to be incorporated into the swine, poultry, fish or shrimp diets, we need to carefully select the proper strain that will do the right job. You would not like to mistake a cow with your husband or wife. It is the same when selecting a bacillus. Not all bacillus will fulfill your expectations. It will depend on genetic potential of each strain.

I encourage to have a look at the video – WHY STRAIN MATTER that illustrate nicely the variability of the Bacillus genus.

To isolate and select the proper strain from the world of Bacillus, we are monitoring each strain performances regarding some ten differentiation parameters.

1. Capacity to rapidly micro-colonize the intestinal epithelium and to create a protective biofilm

Not all Bacillus strains multiply at the same pace. Some do faster than others depending on the substrate they meet. For an effective probiotic to be used in Livestock, we need to select strains with strong properties of multiplication at a pH between 6,5 and 9.

The difficulty of this process of selection is that the conditions in-vivo are often very different than conditions in-vitro. A strain of Bacillus can develop very rapidly in-vitro but struggle to develop at the same pace in-vivo.

To ensure that the probiotics populate and multiply inside the gut lumen, it will need to adhere to the intestinal cells. Not all the Bacillus strains have this capacity and a strict selection is required to identify the strains that populate the gut effectively to increase its retention and avoid being flushed to fast by the transit. This is an important mode of action as the selected Bacillus strains will micro colonize at the strategic place in the gut where pathogens try to develop and to create disruptions.

2. Capacity to produce anti-microbial compounds

Bacteria learns as well to defend themselves against the aggression from other bacteria by producing some lipopeptides with anti-bacterial properties. Some strains of Bacillus are specifically strong in bacteriocin production. Recent experimentations demonstrated the inhibition of some strains agaisnt the growth of E. coli and Salmonella which can very valuable for Swine and Poultry nutritionists searching for alternative to antibiotics.

3- Capacity to produce digestive enzymes

Over years of evolution, bacterias adapted themselves to their environment to survive. To do so, some bacterias acquired the capacities to produce several sort of enzymes, to digest protein, energy, lipids and even fibers. Some strains of Bacillus are producing some proteases that can digest the peptides and amino-acids present in the large intestine. This property is very important when we want to limit the development of proteolytic bacteria like Clostridium spp. and E.Coli that are developing by fermenting undigested protein which result in the production of toxic compounds as ammonia, amines, phenols and sulfides. Some Bacillus showed as well some abilities to produce NSP enzymes. This is very valuable in feed production as it equips the animal with the ability to value better the energy portion from the diet.

Few probiotic manufacturers are able to provide you a matrix by looking at your diet composition. This matrix can be enter into your formulation software to quantity the amount of digestible energy and protein gained from the addition of probiotics and thus reduce your diet cost.

4. Capacity to bind iron

Among the strategy of defense developed by bacteria, they learnt how to develop siderophores. These molecules produced by some strains of Bacillus are binding the iron available in the gut and starve other bacteria who cannot access. By creating a competition for iron, selected probiotics with a superior siderophore production capacity prevent other potential pathogenic bacteria to access it for their metabolism, especially E.Coli and Salmonella spp. which need high level of iron to operate properly that they normally find in high quantity in hemolytic conditions like lesions or enteritis

The selection of the probiotics able to produce the siderophores are confirmed by the measurement of free iron in solution between cultures of different strains of Bacillus.

5. Genomic stability to avoid mutation

This is a very important element to take into account. Bacteria multiply very fast and therefore if the bacteria population is not genetically very homogenous, the transfer of genetic materials between bacteria could lead to mutation. That would mean that after several months or several years, the probiotics could actually evolve into different strains of Bacillus with different properties. This is a scenario that we do not want to face when administering a probiotic to animals.

To maintain the stability of the population, it is essential from the start to select and maintain a very pure population of bacteria in order to limit mutation.

6. Capacity to resist high temperature

In feed manufacturing, thermo stability is an important requirement when we want to mix probiotics in the feed to resist pelleting for Swine, Poultry and Shrimp feed. Live bacteria will die during the process and only sporulated ones will survive. But for an effective probiotics, we need to ensure that the sporulation is strong enough to resist such level of temperature. The process of selection consists in exposing different strains of Bacillus to high temperature and check which strains survive then germinate and multiply the fastest.

7. Capacity to survive antibiotics

Probiotics are under the threat of antibiotics as any other bacteria. The use of antibiotics in the feed can annihilate their action. Only the probiotics that are under the forms of spores will survive the presence of antibiotic. Only some sub-strain of Bacillus probiotics will get their spores to germinate at different moment in the gut to repopulate the gut every time that the presence of antibiotic will disrupt the flora. It is an endless cycle between the antibacterial effect of feed antibiotic and the germination of new spores.

Given the variability of the world of Bacillus, it is essential to confirm that the probiotic that you are purchasing has been selected based on these differentiating parameters to ensure that you are using a champion to take care of your animals.


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