Our new paper on the relationship of gut microbiota and presence of low molecular weight compounds in caecal digesta of one-week-old chickens has been just published in the Poultry Science. A general conclusion is that colonisation of the chicken caecum with Bacteroides, Megamonas, Megasphaera, Phascolarctobacterium, Succinatimonas or Sutterella (gut anaerobes) leads to release of additional molecules of plant origin from the feed into digesta. Digesta of chicks colonised by gut anaerobes was enriched for derivates of nucleotides and amino acids, and products of their fermentation. Digesta of chicks colonised by gut anaerobes was enriched also for biologically active molecules like daidzein, genistein, glycitein, nicotinamide, feruloyl putrescine or feruloyl agmatine. There were also some exceptions confirming this rule, e.g. glutamate and tyramine were more abundant in caecal digesta of control chickens. Similarly, betaine or soyasaponin I dominated in digesta of control chickens in comparison to those colonised by gut anaerobe mixture.
We are still considering placement of this knowledge since increased abundance of a given metabolite is a compromise between degradative function of gut microbiota of feed ingredients associated with release of additional molecules, metabolic function of gut microbiota and their ability to ferment just released amino acids or nucleotides, ability of chickens to resorb newly available nutrients and ability of chickens to secrete their own metabolites in caecal digesta. Increased abundance of daidzein, genistein or glycitein, all soya flavonoids, therefore indicates inability of chickens to resorb them in such an amount. On the other hand, disappearance of betaine in digesta of chicks colonised by gut anaerobe mixture indicates that at least one of them can utilise and degrade betaine. Despite such uncertainties, a mere fact that the composition of gut microbiota extensively modifies composition of low molecular weight compounds means that it is possible to enrich digesta for biologically active molecules by a combination of feed formula modification and administration of defined mixtures of selected gut microbiota members.