Lactulose in combination with soybean lecithin has a cryoprotective effect on probiotic taxa of bifidobacteria and Lactobacillaceae.

Lactulose is commonly used in pharmacy for constipation and hepatic encephalopathy treatment. The prebiotic effect of lactulose is also often mentioned. However, its cryoprotective effect in combination with lecithin on the main representatives of probiotics has not been tested yet. The 12 taxa of bifidobacteria and Lactobacillaceae members were used for the purpose. These were mixed in a ratio of 1:1 with lactulose + lecithin (finally 5.0% and 1.25%, respectively; LL). The 25% glycerol (G+) solution and cultures themselves were applied as positive and negative controls, respectively. Bacterial suspensions were stored at a mild freezing temperature (-20°C) until the end of the experiment (210th day). The LL solution had a comparable (insignificant difference at the P-value = 0.05) cryoprotective effect as the positive control in five of six bifidobacteria and in three of six representatives of Lactobacillaceae. The better cryoprotective effect was revealed in other Lactobacillaceae. At the end of the experiment, the generally accepted therapeutic minimum (>107 Colony Forming Units/mL) was determined in LL solution in five bifidobacteria and four Lactobacillaceae strains. The presented results improve knowledge about long-term mild cryopreservation of the most commonly used probiotics and could contribute to developing new forms of (nutri)synbiotics.

Colonization of Germ-Free Piglets with Mucinolytic and Non-Mucinolytic Bifidobacterium boum Strains Isolated from the Intestine of Wild Boar and Their Interference with Salmonella Typhimurium.

Non-typhoidal Salmonella serovars are worldwide spread foodborne pathogens that cause diarrhea in humans and animals. Colonization of gnotobiotic piglet intestine with porcine indigenous mucinolytic Bifidobacterium boum RP36 strain and non-mucinolytic strain RP37 and their interference with Salmonella Typhimurium infection were compared. Bacterial interferences and impact on the host were evaluated by clinical signs of salmonellosis, bacterial translocation, goblet cell count, mRNA expression of mucin 2, villin, claudin-1, claudin-2, and occludin in the ileum and colon, and plasmatic levels of inflammatory cytokines IL-8, TNF-α, and IL-10. Both bifidobacterial strains colonized the intestine comparably. Neither RP36 nor RP37 B. boum strains effectively suppressed signs of salmonellosis. Both B. boum strains suppressed the growth of S. Typhimurium in the ileum and colon. The mucinolytic RP36 strain increased the translocation of S. Typhimurium into the blood, liver, and spleen.