Physiological, biochemical, and functional characterization of Lactiplantibacillus plantarum strain CAU5271 as a dairy probiotic with a Gaussian Process Regression (GPR) model for stress tolerance prediction

The present study focused on the Lactiplantibacillus plantarum strain CAU5271, identified through molecular methods and 16S rRNA gene analysis. It assessed the strain’s morphological, physiological, and biochemical properties, including its fermentation capabilities with 49 types of carbohydrates, enzymatic activity, and survival rates at various pH levels (2.5, 4, 5.5) and bile salt concentrations (0.3%, 0.5%, 0.7%). The results confirmed that strain CAU5271 is Gram-positive, catalase-negative, non-spore-forming, and non-motile. It effectively fermented several carbohydrates (e.g., glucose, lactose) making it suitable for producing fermented foods like yogurt and cheese. However, its survival rate decreased with increased acidity, bile salt concentration, and storage time. Additional evaluations covered growth rates at different NaCl levels and temperatures, survival in simulated gastrointestinal conditions, inhibition of Staphylococcus aureus adhesion, and cholesterol reduction. The strain exhibited favorable characteristics for probiotic food production, suggesting that further clinical studies are needed to advance probiotic product development.This study develops a Gaussian Process Regression (GPR) model to predict acid (pH 2.5–4.5) and bile (0.3–0.7% w/v) tolerance in Lacticaseibacillus rhamnosus SMHA30. The model achieved high accuracy, with R² values of 0.98 (bile) and 0.96 (acidity), and low MAPEs (2.11–2.54% for bile; 3.45–3.78% for acidity), demonstrating GPR’s effectiveness in modeling microbial stress responses for probiotic screening and bioprocess optimization.