Functional, Modeling and Antimicrobial Characterization of Lactobacillus helveticus BGRA43 Isolated from Traditional...

Lactobacillus helveticus strains are recognized as promising dairy starter cultures and probiotics. This study aimed to isolate and characterize L. helveticus BGRA43 from traditional Iranian Khiki cheese and evaluate its functional and probiotic potential. The strain exhibited prominent β-galactosidase activity and fermented key milk sugars (lactose, galactose). It demonstrated robust tolerance to acidic pH and gastrointestinal conditions. Probiotic traits were notable: surface hydrophobicity (62.9%), auto-aggregation (46.6%), and adhesion to Caco-2 cells (13.24%). Co-aggregation with pathogens was highest for Staphylococcus aureus (52.6%). The strain showed substantial cholesterol assimilation (57.67%), comparable to Lacticaseibacillus rhamnosus GG (59.30%). Antimicrobial assays revealed strong inhibitory activity, particularly against Gram-positive pathogens, with MIC values of 6.25-12.5% (v/v) for acidic cell-free supernatant. Safety assessment confirmed γ-hemolysis, DNase negativity, and a favorable antibiotic susceptibility profile. The results demonstrate that L. helveticus BGRA43 possesses a high potential for application as a functional dairy starter and probiotic, with performance metrics comparable or superior to the established probiotic GG in key properties such as acid tolerance and cholesterol reduction. In the second section of this study, Gaussian Process Regression (GPR) applied to predict bile tolerance and acidity. The GPR model demonstrated high accuracy and robustness, which facilitated the identification of a bacterial strain with promising potential for probiotic applications and industrial process optimization.