Figure 1.
Generic composition, spatial architecture and metabolic activity of studied microorganisms consortia.
A – Population composition of bacterial consortia (measured with relative abundancy of specific 16S rDNA genes). B – Microscope image of consortia of nitrifying bacteria: AOB (red) and NOB (green), labeled using FISH. C – Metabolic activity of the consortia measured in the presence of ammonium, nitrite, glucose and acetate. Biomass 0.675 mg mL−1, concentration of ammonium 4 mM, nitrite 1.5 mM, glucose 2.8 mM, acetate 8.3 mM, temp 20±1°C, pH 7.5±0.1.
Figure 2.
Change of oxygen consumption rate in the presence of cyanide (A), azide (B), dicumarol (C) and quinacrine (D).
Ammonium concentration 4 mM (AOB), nitrite concentration 1.5 mM (NOB), temp 20±1°C, pH 7.5±0.1.
Figure 3.
Relative decrease of NAD(P)H (with respect to the control) in AOB and NOB cells in the presence of cyanide (2.0 µM), azide (1.5 mM), dicumarol (80 µM) and quinacrine (0.5 mM), relative to the control without inhibitors.
Statistically significant differences are indicated with asterisk. Ammonium concentration (AOB) 4 mM, nitrite concentration (NOB) 1.5 mM, temp 20±1°C, pH 7.5±0.1.
Figure 4.
Plasma membrane potential of AOB (row A), NOB (row B), visualized by JC-1 (8 µM) in the presence of cyanide (100
µM), azide (75 mM), dicumarol (25 µM), quinacrine (1 mM) and control without xenobiotics. Observation started after 30 min. preincubation in the eppendorf with coverslip. Ammonium concentration 4 mM, nitrite concentration 1.5 mM, temp 20±1°C, pH 7.5±0.1.
Figure 5.
Hypothetical schematic of NOB ETCh with marked places of electron flow inhibition where a - quinacrine; b - dicumarol; c - azide and cyanide.
Red arrow shown electron flow from NXR (nitrite oxidase) to oxygen; yellow arrow - reverse electron flow from NXR to NAD(P)+; blue arrow- reverse proton flow. The model was based on the data presented in [12], [17], [18], [47]–[51].