Rhodopseudomonas palustris

cyanobacteria

ammonium inhibition

Water treatment

Pollution

Hydrobiology

Though it is feasible of Rhodopseudomonas palustris (R. palustris) stimulation in the cyanobacterial substrate, less is known about its performance under the high ammonium-nitrogen (NH₄-N) circumstance. In the present study, the performance of grown R. palustris Strain PUF1 under an NH₄-N gradient were investigated. Results showed that both the bacterial density and the pigment synthesis were severely inhibited at an NH₄-N concentration of 6.0 g/L, while the ultrathin structure of survived PUF1 wasn’t obviously changed in comparison to NH₄-N concentration ≤3.0 g/L. Noticeably, at an NH₄-N concentration of 3.0 g/L PUF1s recovered its biosynthesis of pigments in a six-day acclimation period. Importantly, the PUF1s thrived in algal substrate under the NH₄-N concentration ≤1.0 g/L with per mL algal substrate 8.96 to 9.88×10⁸ colony formation unit (CFU) on day six. Moreover, it was more diverse of the bacterial consortia in the low NH₄-N treatments (≤1.0 g/L) than that of NH₄-N concentration 3.0-6.0 g/L. Additionally, the excess NH₄-N reduced the sequestration of phosphorus by PUF1s from the algal substrate. Based on the above findings, an NH₄-N threshold up to 1.0 g/L was recommended, it herein produces substantial R. palustris biomass and achieves efficient nutrient sequestration from the protein-rich cyanobacterial feedstock.