Mangrove-Derived Microbial Consortia for Sugar Filter Mud Composting and Biofertilizer Production

To mitigate the environmental burden of sugar industry filter mud in Guangxi and unlock its resource potential, this study introduces a novel approach leveraging the unique microbial resources of mangrove ecosystems to enhance composting efficiency. Microbial strains were isolated from rhizosphere sediments of mangroves in the Beilun River in Fangchenggang and inoculated into a composting system using sugar filter mud. The results demonstrated that inoculation with a mangrove-derived microbial consortium—represented by the nitrogen-fixing strain P1N2—significantly accelerated and prolonged the thermophilic phase (≥53.6 °C for 12 days), leading to greater organic matter degradation and a reduced carbon-to-nitrogen ratio (C/N = 15.2). High-throughput sequencing revealed distinct microbial succession patterns during composting. It confirmed that the exogenous inoculant reshaped the indigenous microbial community, promoting the dominance of functional taxa, including Ochrobactrum, Bacillus, and Nocardiopsis, at key stages, thereby facilitating efficient humus synthesis. Pot experiments further verified that the resulting compost improved soil structure, stabilized nutrient availability, and markedly increased the yield and quality of Chinese flowering cabbage (Brassica parachinensis). These findings demonstrate that mangrove-derived microbial inoculants serve as potent bio-enhancers, providing an environmentally sustainable and technically feasible pathway for the high-value reutilization of sugar industry filter mud.