Synthetic microbial communities for simultaneous nitrogen removal and pathogen control: probiotic isolation, efficacy analysis, consortium construction and application potential

To address the limited environmental adaptability and instability of single heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria in treating aquatic nitrogen (N) pollution, this study isolated five efficient probiotics from shrimp farming environments. These include two HN-AD strains, Pseudomonas stutzeri GMSN161 and Bacillus subtilis HHEB2, which effectively removed over 91.15 % of ammonia and nitrite from various N sources, demonstrating good environmental adaptability. Two lactic acid bacteria (LAB), Lactiplantibacillus plantarum SDEX1 and SDWX2, produced lactic and acetic acids, significantly inhibiting five aquatic pathogens. Pichia kudriavzevii HHWY1, a yeast, secreted its extracellular polysaccharides and digestive enzymes to provide nutritional supplementation for the synthetic microbial communities (SMCs). To overcome the limitations of single strains, three SMCs (NMY-1, NMY-2, and NMY-3) with N removal and antibacterial functions were constructed. The SMCs exhibited superior N removal rate (>97.51 %) across diverse N sources and broader environmental adaptability compared to single strain systems. Notably, the optimal SMC (NMY-3) maintained over 90 % N removal across a wide range of conditions: 10–40 °C, 0–50 ppt salinity, pH 4.5–9.5, and C/N ratios of 0–20. SMCs also effectively inhibited pathogens, with NMY-3 showing the strongest activity, followed by NMY-1 and NMY-2. When applied to real aquaculture wastewater, all three SMCs removed over 90 % of total nitrogen (TN). This innovative strain combination strategy provides a new paradigm for applying synthetic microbial communities in environmental remediation.