Valorization of Dairy Sludge as a Low-Cost Substrate for Enhanced Biomass and Exopolysaccharide Production by Enterococcus durans K48

Articles in Press

Document Type : Research Article-en

Authors

Nazanin Taheri Nasab ¹

Mohammad Reza Edalatian Dovom ¹

Marzieh Moeenfard ¹

Leila Roozbeh Nasiraei ²

¹ Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

² Department of Food Science and Technology, No.C., Islamic Azad University, Nour, Iran

10.22067/ifstrj.2026.98652.1575

Abstract

Dairy industry waste, particularly organic-rich dairy sludge, represents a promising and sustainable resource for biotechnological applications. This study evaluated the potential of dairy sludge as a cost-effective medium for the co-production of biomass and exopolysaccharides (EPS) by selected Enterococcus strains. The physicochemical parameters of the dairy sludge were first characterized, revealing a composition of 32.70% fat, 29.32% protein, 9.56% ash, and 30.17% carbohydrates (which adjusted to 28.50% after spray-drying). Five strains were screened through a quantitative culture-dependent approach to evaluate their growth and EPS production. Among the tested isolates, Enterococcus durans K48 exhibited the highest production potential and was selected for further study. Response Surface Methodology (RSM) was employed to optimize the concentrations of key medium components: dairy sludge, sucrose, and yeast extract. Under the optimized conditions (15% dairy sludge, 5% sucrose, and 2.5% yeast extract), a maximum biomass yield of 8,440 mg/L and an EPS yield of 394.2 mg/L were achieved. These findings demonstrate that dairy sludge can serve as a viable and sustainable substrate for Enterococcus cultivation, facilitating efficient biomass and EPS production while contributing to the valorization of dairy processing waste.

Keywords

Biomass

Dairy sludge

Lactic acid bacteria

Medium optimization

Valorization

Subjects

• Food Biotechnology

---