Dietary Nitrate: Effects on the health of weaning pigs and Antimicrobial activity on seven probiotic Bifidobacterium spp. strains

The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology. It has been shown that nitrite, under the acidic conditions of the stomach, may kill gut pathogens like Salmonella enteritidis, Escherichia coli, Salmonella typhimurium, and Yersinia enterocolitica, whereas acid alone has only a bacteriostatic effect. An in vivo study was conducted in order to assess the effects of dietary nitrate on microbiota and on the health of the gut (particularly in the stomach and small intestine). 96 weaning pigs were fed a diet containing high nitrate levels (15 mg and 150 mg) and then challenged with Salmonella enterica serovar typhimurium. Differences in composition of the gut microbiota were assessed by analysing samples from the pigs: To date analysis of 48 pigs has been completed.. Preliminary results demonstrated no effect on the population densities of microbial groups either from the challenge or from nitrate intake. However, increasing the time from challenge decreased either the counts of LAB in the stomach and jejunum or of clostridia in the stomach. Bifidobacteria also decreased in the stomach contents as nitrate supplementation increased. Supplementing the feedstuff with high dietary nitrate intake and then challenging with Salmonella did not affect the gastric pH or the degree of ulceration in the pigs. The synergistic bactericidal effects of pH, nitrite and thiocyanate on seven probiotic Bifidobacterium spp. strains were also investigated in an in vitro study. The results of the in vitro study demonstrated that an inhibitory effect exists on the seven probiotic bifidobacteria investigated with an exposure longer than 2 hours and pH values < 5.0. Addition of thiocyanate also increased the susceptibility of the tested strains. In this in vitro study, the most resistant strains at all conditions were B. animalis subsp. lactis Ra 18 and P32 and B. choerinum Su 877, Su 837 and Su 891

Folate production in bifidobacteria from omnivores, herbivores and carnivores

Folates are water-soluble B-group vitamin that are cofactors in many metabolic pathways such as DNA synthesis and methylation pathways. Humans cannot synthesize folate and its low status has been implicated in a wide variety of disorders. Naturally occurring food folates occur in abundance in leafy green vegetables, yeast extracts, citrus fruit, liver and kidney. Folate could derived, other than from diet, from indigenous bacteria of the microbiota which posses the ability of de novo folate production. Intestinal bacteria such as bifidobacteria can produce this cofactor by themselves from simple precursors; howewer some bifidobacteria are auxotrophic and have a strict growth requirement for folic acid. The study of folate metabolism in bifidobacteria isolated from different animals, such as omnivorous, herbivorous and carnivorous, could advances the knowledge of host-interaction in relation to endogenous folate production for possible microbiota modulation. We aimed to investigate the production of folate by bifidobacteria isolated from animals differing in diet in order to assess the potential indigenous contribute of folate availability provided by the microbiota.We aimed to investigate the production of folate by bifidobacteria isolated from animals differing in diet in order to assess the potential indigenous contribute of folate availability provided by the microbiota

Produzione di folato in bifidobatteri: produzione di 5-metil-tedraidrofolato e tetraidrofolato in periodi diversi di crescita

I folati sono essenziali per la sintesi di DNA e proteine. Sono presenti in alcuni alimenti e microorganismi. Il 5-metil-tedraidrofolato e’ una forma di folato piu’ stabile e biodisponibile del tetraidrofolato. Tale ricerca ha studiato il contenuto di 5-metil-tedraidrofolato e tetraidrofolato in specie diverse di bifidobatteri ed in momenti differenti di crescita. Due ceppi di Bifidobacterium longum subsp. longum B2160 e B. breve B1501 appartenenti alla “Bologna University Scardovi Collection of Bifidobacteria” (BUSCOB) sono stati coltivati in terreno privo (FFM) o con aggiunta di folato. Un metodo di HPLC validato e’ stato utilizzato per l’analisi di folati estratti dai bifidobatteri. Bifidobacterium longum subsp. longum B2160 e B. breve B1501 contenevano un quantitativo di tetraidrofolato superiore (2673 e 1718µg/100g di biomassa, rispettivamente) al 5-metil-tedraidrofolato (51 e 62µg/100g) durante la fase di crescita esponenziale. Tale prevalenza non cambiava nel tempo ma il livello di tetraidrofolato diminuiva all’approcciare della fase stazionaria. La quantita’ di 5-metil-tedraidrofolato rimaneva bassa ed indipendente dalla crescita. Tale risultato contrasta con la maggior parte dei ceppi di bifidobatteri finora studiati, dove il 5-metil-tedraidrofolato e’ presente in quantita’ superiori rispetto al tetraidrofolato. Il contenuto di folati e’ dunque dinamico e dipendente dal ceppo e dal suo stato fisiologico. Per una corretta selezione di ceppi probiotici e’ necessario tenere cio’ in considerazione

Effect of probiotic inocula and/or nutribiotics on the population density of lactic acid bacteria in the intestine of weaning pigs

Food safety and health issues increased the need to use alternative procedures to antibiotics to combat pathogens in livestock. We evaluated the potential health-improving effects of both a probiotic and/or prebiotic feed formula in four series of trials. In a first and second experimental series, weaning pigs were fed respectively with different strains of Bifidobacterium spp. as probiotics and different fructo- and galacto-oligosaccharides as prebiotics. The best probiotic strains and prebiotic fiber resulting from these two series were jointly used in a third series. The composition of the cecal microbiota of the weaning pigs was analyzed and in vivo trials were conducted to evaluate the effects of the feed supplements. Bifidobacteria strains with a similar ability to develop in the hindgut had a different effect on the piglet performance depending on the dose in which they were provided. Our data also support that the presence of fructo-oligosaccharides can stimulate the occurrence of bifidobacteria in the cecum. We did however not observe an additional growth stimulus when they were supplemented with an increasing dose of bifidobacteria. In the fourth series of trials the best feed supplementation formula (1011 cfu of a Bifidobacterium animalis subps. lactis twice a day per pig) was challenged by infecting the pigs with a pathogenic strain of Salmonella