The series of concentrations of sodium sulfite (0, 0.25, 0.5, 0.75 and 1 g/l Na2SO3) can make hypoxia environment (Fig.2a). Under the PfnrF8 [6] promoter, the activity of lacZ can be seen to rise markedly from 0 g/l to 1 g/l Na2SO3 (Fig.2c). This promoter can respond our hypoxia environment regularly. Comparing with the FF+20 (mutation) promoter, its downstream gene had much higher expression (Fig.2d). We will debug hypoxic sensitivity of the PfnrF8 promoter in the future.[[File:T--NEFU_China--parts--F8.png|600px|thumb|left|Fig.2(a) Dissolved oxygen change curve under a series of concentrations of sodium sulfite (0, 0.25, 0.5, 0.75 and 1 g/l Na2SO3). (b) Hypoxic induction of FF+20 (mutation) promoter in E. coli Nissle 1917. Expression of lacZ vary in different sodium sulfite concentrations (0, 0.25, 0.75 and 1 g/l Na2SO3). β-gal activity was measured as described in texts above. Values are expressed as percentage of promoter activity at 1 g/l Na2SO3. (c) Hypoxic inductions of PfnrF8 promoter in E. coli Nissle 1917. Expression of lacZ shows the Na2SO3 concentration dependence in increasing sodium sulfite concentrations (0, 0.25, 0.5, 0.75 and 1g/l Na2SO3). β-gal activity was measured as above. Values are expressed as percentage of promoter activity at positive (The mutant of PfnrF8, with strong expressing and not induced by hypoxia). (d) The comparison of Hypoxic inductions of PfnrF8 promoter and FF+20 (mutation) promoter in E. coli Nissle 1917. Expression of lacZ was compared in increasing sodium sulfite concentrations (0, 0.25, 0.75 and 1 g/l Na2SO3). β-gal activity was measured as above. Values are expressed as percentage of promoter activity at positive (The mutant of PfnrF8, with strong expressing and not induced by hypoxia). Error bars represent standard deviations.]]