Abstract
Lactic acid bacteria (LAB) are involved in several food fermentations and many of them provide strain-specific health benefits. Herein, the probiotic potential of the foodborne strain Lactobacillus fermentum MBC2 was investigated through in vitro and in vivo approaches. Caenorhabditis elegans was used as an in vivo model to analyze pro-longevity and anti-aging effects. L. fermentum MBC2 showed a high gut colonization capability compared to E. coli OP50 (OP50) or L. rhamnosus GG (LGG). Moreover, analysis of pumping rate, lipofuscin accumulation, and body bending showed anti-aging effects in L. fermentum MBC2-fed worms. Studies on PEPT-1 mutants demonstrated that pept-1 gene was involved in the anti-aging processes mediated by this bacterial strain through DAF-16, whereas the oxidative stress protection was PEPT-1 independent. Moreover, analysis of acid tolerance, bile tolerance, and antibiotic susceptibility were evaluated. L. fermentum MBC2 exerted beneficial effects on nematode lifespan, influencing energy metabolism and oxidative stress resistance, resulted in being tolerant to acidic pH and able to adhere to Caco-2 cells. Overall, these findings provide new insight for application of this strain in the food industry as a newly isolated functional starter. Furthermore, these results will also shed light on C. elegans molecular players involved in host-microbe interactions.
Highlights
Lactic acid bacteria (LAB) are generally recognized as safe (GRAS) microorganisms mainly involved in various food fermentations [1,2].In recent years, interests in the host health-promoting effects exerted by different LAB strains have been growing
Bacterial strains used in this study were Lactobacillus fermentum MBC2, Lactobacillus rhamnosus GG (LGG, ATCC53103) and Escherichia coli OP50 (OP50), previously obtained from the Caenorhabditis Genetics Center (CGC); probiotic L. rhamnosus GG (LGG) and OP50 were used as control where indicated
The results showed that L. fermentum MBC2 was able to adhere to Caco-2 cells with an efficiency of about 1%, irrespective of the initial bacterial titer (Figure 9A)
Summary
Interests in the host health-promoting effects exerted by different LAB strains have been growing. L. fermentum is a heterofermentative species belonging to the Firmicutes phylum [6]. It is a natural inhabitant of the gastrointestinal tract and is often isolated from both human biological samples (i.e., human breast milk and feces) as well as from dairy and non-dairy sources. The uniqueness of certain strains is to survive the harsh gastrointestinal (GI) tract conditions, such as low pH and high bile concentration, transiently colonizing the host gut, where they can exert health-promoting activities. Increasing evidence points at different strains belonging to this species as promising probiotic candidates [11,12,13], as revealed by recent genomic analysis performed on draft genome sequences [14]
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