In vitro characterization of probiotic properties of isolated and grown co-cultures on halophyte-based substrate

Probiotics are increasingly recognized for their health-promoting effects, yet their performance in unconventional fermentation systems such as halophyte-based substrates remains poorly understood. Halophytes, salt-tolerant plants rich in phenolics and other bioactive compounds, impose selective pressures that may favor robust and stress-tolerant microorganisms. In this study, we assessed the probiotic potential of selected lactic acid bacteria and yeast strains, including Lactococcus (L.) lactis, Bacillus (B.) coagulans ATCC 7050, Saccharomyces (S.) cerevisiae, Kluyveromyces (K.) marxianus DSM 7238, and Cyberlindnera (C.) jadinii DSM 2361 and DSM 70,163, cultivated on halophyte hydrolysates. In addition, newly isolated strains from halophyte biomass, Lactiplantibacillus (Lpl.) plantarum, Levilactobacillus (Lev.) brevis, and Pichia (P.) fermentans, were bioprospected for their probiotic potential and robustness against relevant environmental stressors. Strains were assessed for viability, tolerance to NaCl and phenol, survival under simulated gastrointestinal conditions, cell surface properties (hydrophobicity, autoaggregation, biofilm formation), antioxidant activity, and antimicrobial effects. Results revealed great variability among tested strains. Lpl. plantarum and L. lactis demonstrated high salt (> 70% survivability at 5% NaCl) and phenol tolerance (> 80% survivability at 0.3% phenol), strong survivability in simulated digestion (up to ~ 30% survival for Lpl. plantarum and < 10% for L. lactis), and notable antimicrobial activity against up to three tested pathogens, as well as antioxidant activity (up to ~ 55% DPPH scavenging). K. marxianus exhibited high stress tolerance, enhanced antioxidant capacity (up to ~ 70% DPPH scavenging), high survivability after simulated digestion (> 100%), and inhibition of several pathogens. Conversely, B. coagulans showed broad antibiotic resistance, low gastrointestinal survivability (< 5%), and poor growth in halophyte-based media. Overall, Lpl. plantarum and K. marxianus emerged as the most promising candidates for probiotic development and biotechnological applications. These findings highlight halophyte biomass as a selective substrate that favors resilient strains with desirable probiotic traits, supporting its potential in developing sustainable, plant-based fermentation systems. Lpl. plantarum and L. lactis showed robustness and bioactive properties. K. marxianus exhibited high stress tolerance and probiotic potential. B. coagulans ATCC 7050 appears least promising probiotic.