Beyond musical chairs for microbes – the transition from probiotics to active microbials

Probiotics have evolved. From isolates of such exotic origins as lychee peels and baby’s nappies they have come a long way. Today’s active microbials do not just compete with pathogens for feed or attachment sites. In addition they actively modulate the growth of potential pathogens such as Clostridia down and Lactobacilli up. This is of particular interest as Lactobacillus and relatives are notoriously difficult to deliver into the intestine alive. By contrast spore forming Bacilli are very durable, both during feed processing and passing through the digestive tract.

The most widely accepted definition of a probiotic is "a live micro-organism which, when administered in adequate amounts, confers a health benefit on the host". Probiotics have long been proposed as a natural solution to stabilise the gut flora. Candidates such a Lactobacilli and yeast were selected from the most unlikely sources, such as lychee peel by Boulard in 1923. Already in 1935 the first product that claimed a probiotic effect (Yakult) was commercially available to humans.

In decades of research it has been proven that the proven probiotics have certain features in common.

• They compete with pathogens for nutrients and attachment sites in the gut.
• They help regulate the hosts immune response.
• Many have a decreasing influence on pH in the small or large intestine.

Organisms which do not display all or any of these may not cause the hosts any harm, but have no way to confer benefit to the host either.

Active microbials
The concepts of active microbials is newer and most importantly more specific than probiotics. Rather than just taking the space of pathogens, active microbials can directly affect specific groups of potential pathogens. This was originally demonstrated by Nissle in 1917. Nissle described and isolated a strain of Escherichia coli from the faeces of a man unaffected by an outbreak of shigellosis. This was so successful as a treatment that the strain is still available to treat shigella and salmonellosis in humans today.

Microbial strains are uniquely adapted to their host and its diet. So in order to have the most efficient poultry probiotic human strains from humans or soil are only the second best choice. Kemin’s active microbioal CLOSTAT® was selected from the gut of healthy chickens during an outbreak of necrotic enteritis. The following in-vitro studies confirmed it does, unlike other Bacillus strains, not only displace potentially pathogenic Clostridium species, but can modulate their proliferation directly.

Why should we influence the gut microbiome in the first place
The gut microbiom is in function almost an additional organ. It is key to nutrient uptake, vitamin synthesis and regulates the immune response, water balance and more. Even a slight, subacute disbiosis will lead to large economic losses in livestock. The most controlled way to balance the microbiome, and to stop potential pathogens overgrowing, is an active microbial. The ideal active microbial is native to the species and selected with the most important pathogens in mind and ideally tolerant to the drugs commonly used in the species.

What can you expect to see?
Active microbials are perfect probiotics.

They improve feed conversion, encourage the growth of beneficial organisms such as Lactobacilli affecting pH in the small intestine. As a result of the flora change villi and crypt structures are visibly improved, and pathogens reduced. Beyond the scope of a perfect probiotic this active microbial can help to manage the potential pathogenic organism it has been selected against. For CLOSTAT® that would be for example strains of pathogenic Clostridia.