Probiotic characterization of Magnusiomyces capitatus OY151 from Egyptian cottage cheese and therapeutic evaluation of its postbiotic metabolites

Abstract Probiotics are live microorganisms that provide health benefits by modulating the gut microbiota through their bioactive metabolites, known as postbiotics. In this study, Magnusiomyces capitatus OY151 was isolated and evaluated for its in vitro probiotic potential. The yeast strain was assessed for tolerance to temperature, acidic pH, bile salts, and simulated gastrointestinal conditions, as well as cell surface hydrophobicity (CSH), auto-aggregation, co-aggregation, hemolytic activity, and antibiotic susceptibility. Furthermore, its exometabolomic profile was characterized using UPLC-qTOF-MS/MS, and its potential therapeutic activities were investigated. The M. capitatus OY151 strain exhibited high survival rates under harsh conditions, such as acidic pH 2.5 (86.66 ± 1.52%) and 2% bile salts (84.67 ± 0.58%). It also showed strong tolerance to simulated gastrointestinal environments containing amylase, pepsin, and trypsin, with survival rates of 96.34 ± 0.57%, 86.58 ± 0.52%, and 83 ± 1%, respectively. The CSH percentages reached 80.82 ± 0.75%, 44.23 ± 0.68%, and 23.71 ± 0.62% with chloroform, xylene, and hexane, respectively. Auto-aggregation increased with time from 86.63 ± 0.55% to 90.55 ± 0.51%, while co-aggregation with E. coli , B. subtilis , and S. aureus reached 72.15 ± 0.79%, 61.66 ± 0.57%, and 61.6 ± 0.53%, respectively. Additionally, the preliminary safety studies of this strain showed reasonable results. Metabolomic analysis revealed diverse bioactive compounds that contribute to its multifunctional therapeutic potential, including amino acids, fatty acids, indoles, organic acids, quinones, phenolics, and peptides. The extract showed antitumor activity against HT-29 and Caco-2 colon cancer cell lines with IC 50 values of 55.7 ± 4.7 and 67.5 ± 3.2 µg/ml, respectively. Otherwise, the cytotoxic concentration CC 50 value against human lung fibroblasts (WI38) was 905.4 ± 16.7 µg/mL, with a selectivity index (SI) of 16.2, confirming its safety against normal cells and its cytotoxic effect against cancer cells. It also exhibited antioxidant, antidiabetic, and anti-inflammatory activities (IC 50 values: 59.1 ± 1.43, 63.2 ± 1.7, and 8.1 ± 0.65 µg/ml, respectively). Furthermore, the extract’s antibacterial activity outperformed the antibiotic control (gentamicin) against several tested bacterial pathogens. This study emphasizes M. capitatus OY151 as a promising probiotic candidate with high tolerance to gastrointestinal conditions, good adhesion properties, and potential therapeutic applications.