Probiogenômica de Lactobacillus delbrueckii CIDCA 133

Abstract

Lactobacillus delbrueckii subsp. lactis CIDCA 133 is a bacterium that has probiotic and therapeutic properties reported only by in vitro studies. There is no scientific evidence about the probiotic potential of this strain in vivo, as well as which proteins and molecular mechanisms would be related to its beneficial effects and its safe status for consumption. Genomic-level analyses, coupled with in vitro and in vivo studies, have been used to characterize new probiotic candidates, and provide new insights into the key genetic factors and molecular mechanisms associated with the functional and safety characteristics of these microorganisms. Thus, with the probiogenomic approach, this study characterized the probiotic profile of CIDCA 133 in vivo, using a model of intestinal inflammation, and investigated the possible genes associated with beneficial and safety effects for future probiotic applications. The in vivo study demonstrated that CIDCA 133 is a potential probiotic strain capable of ameliorating histopathological inflammatory damage in the intestinal mucosa induced by the chemotherapeutic agent 5-Fluorouracil. CIDCA 133 also exhibits immunostimulatory properties capable of increasing gene expression of anti-inflammatory cytokines Il10 and Tgfb1 and inhibition of markers associated with activation of the NF-κB inflammatory pathway. These effects may be associated with secreted, membrane/bacterial surface proteins identified in silico and ratified in vivo, in which it was observed that even after heat inactivation, CIDCA 133 maintains anti-inflammatory effects, demonstrating that this property can be attributed to proteinaceous and non-proteinaceous components present on the cell surface. Many of these genetic factors were also identified, through comparative genomics, in other probiotic strains of the species, and the PrtB protein seems to be the target candidate responsible for the anti-inflammatory properties of the probiotic strains of L. delbrueckii. Phenotypic assays also demonstrated that CIDCA 133 survives acid, osmotic, and heat stress. Furthermore, this strain exhibits antibacterial activity against pathogenic bacteria, possibly through bacteriocins and the production of organic acids such as lactate, whose genes were identified in silico. On the other hand, regarding safety, the genomic analysis showed that CIDCA 133 contains genes associated with virulence, toxic metabolites, and antimicrobial resistance. However, none of these genes is inserted in prophage and plasmid regions. At the phenotypic level, antimicrobial resistance of CIDCA 133 to the antibiotics streptomycin and gentamicin was observed, but no hemolytic activity and mucin degradation was exhibited by the strain. Furthermore, no adverse effects were observed in the clinical and histopathological analysis of healthy mice after consumption of the strain (5 x 10^7 CFU/mL) for 13 consecutive days. Overall, the findings of the present work show that CIDCA 133 exhibits beneficial functional characteristics in vivo and reveals that this strain presents a certain level of safety to be explored for consumption and future probiotic applications.