Biological production and simulated moving bed purification of streptothricin F from food waste digestate†

Abstract

Globally, a significant amount of food waste is generated annually, representing a considerable potential resource. Anaerobic digestion for producing methane is the most effective method for utilizing food waste resources. However, the by-product, food waste digestate (FWD), is rich in C/N/P. Direct discharge of FWD may cause significant environmental burdens and lead to the loss of valuable resources. In this study, we established a system to convert FWD into the high-value agricultural antibiotic streptothricin F through biological fermentation by Streptomyces lavendulae and simulated moving bed (SMB) separation for energy and resource recovery. After biological fermentation, the concentration of streptothricin F in the co-fermentation of FWD and soluble starch by Streptomyces lavendulae reached 0.5144 g L⁻¹, and its concentration was 60.51 times higher than in the control. The COD conversion rate reached 82.50% after biological fermentation, achieving high-value utilization and harmless treatment of FWD. Streptothricin F was effectively separated using SMB technology, achieving a high purity of 97.47% and a recovery rate of 91.16%. Additionally, streptothricin F showed inhibitory effects against Alternaria, Fusarium oxysporum, and Colletotrichum, indicating its broad-spectrum antifungal properties. The pure streptothricin F obtained through SMB separation against Alternaria had an EC₅₀ value of 0.66 μg mL⁻¹, representing an 81.24 times improvement in antifungal activity compared to the unpurified fermentation broth (53.62 μg mL⁻¹). Life Cycle Assessment (LCA) results indicated that the system had a relatively low environmental impact. This research presents a novel strategy for the high-value utilization of food waste digestate, advancing the technological level of biomass utilization.