Co-cultivation of lactic acid bacteria and fodder yeasts for probiotics and postbiotics production on halophyte-based hydrolysate

This study explores the potential of probiotic bacteria-yeast co-cultivation to enhance microbial growth and postbiotic production using halophyte-based media. Initial screening of six yeast strains revealed variations in nutrient utilization, with Saccharomyces cerevisiae, Kluyveromyces marxianus DSM 7238, and Cyberlindnera jadinii DSM 2361, demonstrating superior carbon source consumption and biomass production. Co-cultivation with Bacillus coagulans ATCC 7050 enhanced overall product formation, whereas Lactiplantibacillus plantarum DSM 13272 had undesirable effects on product formation. Optimization trials demonstrated that increasing the total inoculum size to 10 % (v/v) and extending cultivation to 72 h significantly enhanced product yields in selected bacteria-yeast co-cultures, enabling complete utilization of the available carbon sources. Specifically, the best performing combination of B. coagulans ATCC 7050 and K. marxianus DSM 7238 achieved 17.5 g of cell dry weight, 6.9 g of crude protein, and 42.2 mg of vitamin B12/L in halophyte-based broth. Advanced statistical analysis revealed that yeast-driven deacidification played a critical role in improving culture conditions, reducing organic acid stress, and promoting microbial growth. The findings suggest that bacteria-yeast interactions in co-cultures under non-sterile conditions contribute to enhanced fermentation efficiency, with yeast potentially acting as a detoxifier. This study underscores the viability of bacteria-yeast co-cultivation for sustainable probiotics and postbiotics production using halophyte hydrolysate as a production medium and lays the groundwork for future process optimization and industrial-scale applications in alternative protein and nutraceutical development.