No abstract

ObjectiveTo assess the variability of secretory immunoglobulin A (S-IgA) in the lumen and feces of mice along a working day.ResultsMice were maintained under a 12 h light–dark cycle, light period starting at 8 AM. S-IgA was determined in feces and intestinal content (after one or three washes) at three points along the day: at the beginning, in the middle and at the end of the light period (ELP). Significant reduction in the content of S-IgA in the small intestine fluid and in feces was observed at the end of the light cycle, which coincides with the end of a regular working day (8 PM) in any given animal facility. It was also observed that three washes of the small intestine were more effective than one flush to recover a significant higher amount of S-IgA, with the smallest coefficient of variation observed by the ELP. A smaller CV would imply a reduced number of animals needed to achieve the same meaningful results. The results may be useful when designing animal trials for the selection of probiotic candidates based on their capacity of activating S-IgA, since it would imply a more rational use of experimental animals.

Breast milk can be a source of potential probiotic bacteria, but the technological capacity of isolates obtained from this source is not always guaranteed. We aimed at isolating lactobacilli from breast milk samples collected in Argentina, focusing on isolates with functional and technological potential as probiotics. Fourteen Lactobacillus and one Bifidobacterium isolates were obtained from 164 samples donated by 104 mothers. The isolates preliminarily identified by MALDI-TOF, and then the identity was confirmed by partial 16S rRNA gene sequencing. Hydrophobicity was determined (hexadecane and xylene partition). The strains were also co-cultured with murine RAW 264.7 macrophages for screening the capacity to induce the anti-inflammatory cytokine interleukin (IL)-10. Hydrophobicity ranged from 7.4 and 95.9%. The strains Lactobacillus gasseri (70a and 70c) and Lactobacillus plantarum (73a and 73b) were the strains with a higher capacity to induce IL-10 production by macrophages. The technological application was evaluated by freezing dried in 10% lactose or 10% polydextrose. The survival was assessed after accelerated (37 °C, 4 weeks) or long-term (5 and 25 °C, 12 months) storage. Except for Lactobacillus gallinarum 94d, strains lost less than 1 Log10 order cfu/g after long-term (12 months) storage at 5 °C in lactose and polydextrose as protectants. A low correlation between survival to accelerated and long-term storage tests was observed. L. gasseri (70a and 70c) and L. plantarum (73a and 73b) deserve further studies as potential probiotics due to their capacity to induce IL-10 from murine macrophages and their hydrophobicity. In special, L. plantarum 73a was able to confer enhanced protection against Salmonella infection by promoting the immunity of the small intestine.