Exploring the Probiotic Potential and Safety of a Locally Sourced Lactobacillus fermentum Strain Isolated from Dahi, a Traditional Dairy Product

Probiotics are live microbes that offer potential health benefits to the host, including modulation of the host immune system, improvement of anti-inflammatory response, enhancement of antibacterial and anti-allergic properties, as well as anti-proliferative properties. These beneficial microorganisms can interact with the gut microbiota to restore an impaired gut microbiome. While probiotics can be sourced from various sources, this study focuses on isolating and characterizing novel probiotic strains from dairy sources, specifically Dahi. To evaluate the probiotic potential of these isolates, various biochemical, morphological, and physiological tests were performed, followed by 16S rRNA gene sequencing to genotype the isolates. The tolerance of the isolates to pH, temperature, and bile salt, as well as their antimicrobial and adhesion ability, was evaluated. The results showed that the identified novel probiotic strains belonged to the Lactobacillus fermentum species, exhibited remarkable tolerance against bile salts, acidic environments, and temperature, and had excellent adhesion ability, indicating their potential as probiotic strains. Additionally, all isolates were non-hemolytic and displayed significant antimicrobial activity against antibiotic-resistant pathogens, such as Escherichia coli and Staphylococcus aureus . The anti-cancer activity of all isolates was also evaluated against the Human colorectal adenocarcinoma cell line (Caco-2), and all isolates showed significant anticancer activity. These findings validate the beneficial therapeutic values of novel probiotic strains isolated from dairy sources, specifically Dahi, and suggest that they could be used in food and drugs to treat various diseases.