Resource utilization of livestock biogas slurry using a sequential synthetic microbial community-microalga Chlorella...

Intensive livestock farming generates over 2 billion tons of biogas slurry annually, and this effluent typically had total nitrogen of 56.5-830 mg/L and total phosphorus of 0.2-476 mg/L. Without proper management, biogas slurry would contaminate soils and waters. To strengthen the resource utilization of livestock biogas slurry, this study constructed a sequential synthetic microbial community (SynCom)-microalgae coupling system, in which an autochthonous microalga Chlorella sorokiniana isolated from the slurry. The system operated stably for 60 days and achieved 94.41% removal of nitrate nitrogen, 81.84% removal of total phosphorus, and 6.31% removal of chemical oxygen demand. Notably, compared to the BG11 group, SynCom pretreatment increased the biomass and soluble protein content of C. sorokiniana by 27.15% and 488.10%, respectively. Transcriptomic analysis showed that the expression levels of key genes Rubisco and glutamine synthetase were upregulated, with log₂FC values of 2.52 and 1.34, respectively. Therefore, this study provides an efficient biological strategy for simultaneous pollutant abatement and resource recovery of livestock biogas slurry.