Dnitrification-syn-24h-7%

To evaluate the compositional stability of the synthetic bacterial community, cultures were incubated under salinities of 7%, with or without the addition of 20 mg/L NO₃⁻-N, and maintained at 25 °C in a static biochemical incubator for 24 h and 48 h. After incubation, samples were centrifuged at 4500 rpm for 10 min to collect cell pellets, which were then rapidly frozen in liquid nitrogen. The frozen samples were kept on dry ice and sent to Novogene Bioinformatics Technology Co., Ltd. (Beijing, China) for 16S rRNA gene amplicon sequencing. Sequencing was performed on the Illumina NovaSeq 6000 platform using a paired-end 250 bp (PE250) strategy, generating approximately 8 Mb of data per sample.The quality of the sequencing data was assessed using the NGS QC Toolkit (version 2.3.3; Patel & Jain, 2012) with default parameters. High-quality reads were subsequently processed using Parallel-META (version 3.5.3; Jing et al., 2017) with the required parameters specified for taxonomic classification, community diversity estimation, and structural analysis based on 16S rRNA gene sequences. The resulting data were used to calculate the relative abundances of the three component strains within the synthetic community.