In vitro assessment of safety and functional probiotic properties of Lactobacillus mucosae strains isolated from Iranian native ruminants intestine

Abstract

The search for host isolated probiotic bacteria from animal intestine may discover new probiotic candidates with promising health properties. This study evaluated the safety and functional probiotic potential of the lactic acid bacteria (LAB) isolated from the Iranian native ruminants intestine under in vitro assays. The isolates were selected according to criteria including survivability in low pH, bile salts, pancreatic enzymes, different temperatures, NaCl concentrations, antibacterial activities, presence of adhesion genes and safety characteristics. The selected LAB were then identified to species level using 16S rRNA gene sequencing. The results showed that out of one hundred and eighty-seven LAB isolates, only six strains (NABRII50, NABRII51, NABRII52, NABRII53, NABRII54 and NABRII55) were tolerant to low pH, bile salt, pancreatin enzyme, 45 C temperature and 2% sodium chloride. The six selected isolates belonged to Lactobacillus mucosae. Two of the adhesion genes (mub and map) were detected in all strains except NABRII53. The virulence factors were observed in NABRII50, NABRII53 and NABRII55. The tetracycline resistance gene (tet (S)) was detected in NABRII55. This study was the first effort to select Lb. mucosae strains with the probiotic potential from the Iranian ruminants intestine. These results revealed that the ruminant intestinal ecosystem could be considered as a valuable origin of probiotic candidates and all the selected LAB strains except NABRII50, NABRII53 and NABRII55 could be considered as promising probiotics. HIGHLIGHTSLactobacillus mucosae strains isolated from Iranian native ruminants intestine including NABRII51, NABRII52 and NABRII54 showed probiotic potential under in vitro assays. The Lb. mucosae strains including NABRII51, NABRII52 and NABRII54 were able to survive in intestinal physiological conditions, and carried the adhesion genes, such as mub and map. In vitro biosafety assays confirmed that Lb. mucosae strains (NABRII51, NABRII52 and NABRII54) were safe to further studies.

The Probiotic Properties and Safety of Limosilactobacillus mucosae NK41 and Bifidobacterium longum NK46

“…As shown in Table 4, both strains were sensitive to all the tested antibiotics. In previous studies, some strains of L. mucosae were found to be resistant to tetracycline, gentamicin, vancomycin, streptomycin, clindamycin, and erythromycin [11,23,29]. B. longum KABP042, isolated from the feces of healthy children, showed resistance to erythromycin and clindamycin [46].…”

“…The strains that are to be used as probiotics must survive the harsh conditions of the GIT to exert health-promoting effects on the host [28]. A series of in vitro assessments such as resistance to acids, bile salts, and pancreatin have been regarded as reliable indicators for evaluating the probiotic properties of bacterial isolates [11]. In this study, the GIT resistance of L. mucosae NK41 and B. longum NK46 was investigated under a continuous model of simulated gastrointestinal fluid (Table 2).…”

“…The ability of probiotics to adhere to the host intestine is regarded as a pivotal factor in enhancing their health benefits [11]. Furthermore, their adhesion ability allows probiotics to prolong their survival in the GIT and promote interactions between the bacteria and the host [39].…”

“…Additionally, a series of in vitro tests have been devised and employed as criteria for selecting potential probiotics [8]. Among these, a few prerequisites for selecting probiotics for human consumption include resistance to gastrointestinal stress, adherence to gut epithelial cells, and safety aspects, such as the absence of hemolysis, antimicrobial sensitivity, and non-production of virulence factors and biogenic amines [10,11].…”

“…Similarly, probiotic strains require bile tolerance to successfully pass through the small intestine. Additionally, the ability of probiotic strains to adhere to the intestinal epithelial cells is crucial for their colonization and persistence in the gastrointestinal tract (GIT) [11]. The adhesion mechanisms of probiotics involve complex processes, including nonspecific physical binding such as hydrophobicity and interactions with specific cell wall components [13].…”