The probiotic potential of microorganism strains: A comprehensive study

Probiotics are live microorganisms that exert beneficial effects on the host by modulating the gut microbiota and synthesizing bioactive compounds. Of particular importance are metabolites involved in energy metabolism, including compounds of the tricarboxylic acid cycle and B vitamins, which act as coenzymes. This necessitates the search for strains with pronounced metabolic activity and resistance to gastrointestinal conditions. We aimed to comprehensively evaluate the in vitro probiotic potential of specific microbial strains for their subsequent use in dietary supplements and functional foods. We studied the following strains: Propionibacterium troenii (B-6083, B-6080), Weissella thailandensis (B-10412), Bifidobacterium bifidum (AC-1779), Bifidobacterium longum (AC-1257), Pediococcus acidilactici (B-7509, B-7533), and Enterococcus faecium (B-4054). The commercial probiotics “Hemopropiovit” and “Bifiform” were used as the controls. The strains’ antibiotic resistance was determined by the disk diffusion method, their survival in the gastrointestinal tract was measured spectrophotometrically, their antagonistic activity was analyzed by the agar diffusion method, while the compositions and contents of microbial metabolites were identified by high-performance liquid chromatography. The strains were sensitive to antibiotics (inhibition zones > 21 mm), with the highest values recorded for B-6083 (50.6 ± 4.1 mm). High resistance to bile was demonstrated by B-7509 and B-7533 (optical density 2.288 ± 0.049 and 2.364 ± 0.028 at 0.5% bile), as well as B-4054 (optical density 1.242 ± 0.005 at 40.0% bile). The strains AC-1257, B-7509, and B-7533 showed resistance to 6.5% NaCl. The most pronounced antagonistic activity was demonstrated by B-6083 against Escherichia coli (inhibition zone 29.47 ± 0.50 mm) and by B-7533 against Bacillus cereus (23.07 ± 0.47 mm). The strains exhibited high metabolic activity such as synthesizing bioactive compounds. The highest content of vitamin B1 was found in B-10412 (23.10 ± 0.44 mg/g), while succinic acid predominated in B-6080 (432.2 ± 8.2 mg/L). The highest total contents of amino acids were observed in B-7509 (145.2 mg/g) and B-10412 (142.1 mg/g). Some strains showed high probiotic potential by demonstrating resistance to stress factors and exhibiting high antagonistic activity. The strains B-7509, B-7533, AC-1257, B-10412, B-4054, B-6083, and B-6080 possess significant probiotic potential and may be considered as promising components for dietary supplements and functional foods. However, further research is needed such as in vivo studies in rodents.