Cheese whey wastewater-derived Chlorella biomass promotes growth and β-galactosidase activity of Pediococcus sp. isolated from Gundurk

Background Cheese whey wastewater (CWW), a nutrient-rich dairy waste, poses significant environmental concerns because of its high organic load. Valorizing such waste streams through microalgae cultivation provides a sustainable avenue for generating functional biomass for food biotechnology applications. Lactic acid bacteria (LAB) are used as starter cultures, probiotics, and microbial cell factories. Supplementing the LAB culture medium with microalgae may enhance both the growth and functional properties of these bacteria. In this study, we explored the effects of freshwater Chlorella sp. biomass on the growth and functional properties of Pediococcus sp., isolated from the traditional fermented food ( Gundruk ) of Nepal. Results Chlorella cultivated in standard Bold’s basal medium (BBM) or 20% (v/v) CWW medium presented comparable growth rates, with cell densities of 1.59 × 10 ⁷ and 1.73 × 10 ⁷ cells/mL, respectively, on day 8. Fourier-transform infrared (FTIR) spectroscopy revealed an increase in lipid-associated peaks (2970 − 2850 cm ^− 1 ) in the biomass grown in CWW medium. Compared with 18.34 Miller units in the control de Man, Rogosa, Sharpe (MRS) medium, supplementation with Chlorella biomass significantly increased the growth of Pediococcus sp. and increased β-galactosidase activity to 49.33 and 38.82 Miller units when supplemented with BBM-cultured and CWW-cultured Chlorella biomass, respectively. Conclusion These findings demonstrate that microorganisms originating from distinct ecological niches can be used in a unified system for waste valorization and functional fermentation. CWW supports the cost-effective cultivation of Chlorella and provides functional biomass that enhances LAB performance. This finding highlights the potential of combining freshwater microalgae with beneficial bacteria from traditional fermented foods to support the bioremediation of dairy wastes and enhance the development of functional foods.