Recruiting high-efficiency denitrifying consortia using Pseudomonas aeruginosa

Synthesizing the microbial community with a high denitrifying capacity is the key for achieving efficient removal of nitrogen species in wastewater treatment plants. Here, we integrated the evolutionary top-down enrichment and bottom-up bioaugmentation to construct a high-efficiency Pseudomonas-recruited denitrifying consortium (PRDC). A PRDC with a high specific denitrification rate of 109.49 ± 10.58 mg N/(g MLVSS·h) was enriched after 181 days of microbiota construction with pre-inoculation of Pseudomonas strain onto carriers. The 16S rRNA gene sequencing analysis suggested that the pre-inoculated Pseudomonas was quickly washed out and replaced by dominant denitrifying genera, such as Halomonas and Thauera, under different hydraulic retention times (HRTs). The pre-inoculated Pseudomonas can facilitate PRDC by providing public goods, but compromising its nutrient requirements. The dominant community assembly processes switched from homogeneous selection to ecological drift and dispersal limitation under shortened HRT. Furthermore, a shortened HRT facilitated the colonization of new immigrants and intensified their competition with the pre-existing dominant denitrifiers. The PRDC carriers achieved a 1.65-fold enhancement in sludge denitrification and reduced the corresponding chemical oxygen demand consumption at a carrier filling ratio of 30%. Overall, our study developed a novel technique using Pseudomonas aeruginosa as a trigger to enrich high-efficiency denitrifying consortia for wastewater treatment.