Introduction

In this anaerobic experiment we add nitrite (NO₂^- ) in a series of spikes to an untransformed strain of E. coli and to an untransformed strain of P. aeruginosa, and to a strain of E. coli transformed with the Nir gene from P. aeruginosa in order to characterize how readily nitrite is converted to nitric oxide (NO), and subsequently to nitrous oxide (N₂O). We also monitor nitrite, ammonia and nitrate concentrations before each spike. The concentrations of both gasses are measured continually, and the ammonia, nitrite and nitrate concentrations are measured at a series of time points around the spike.

Methods

For the calibration of the electrodes we follow the Calibration protocol

The procedure is based on Experiment 2

Results

In the following diagrams, vertical lines indicate the time at which we spiked with nitrite.

Untransformed E. coli -- Round 1

Mg of Nitrogen (as nitrite or nitrous oxide) per litre measured for varying concentrations of Nitrite added at t=0. All experiments were performed anaerobically.

Untransformed E. coli -- Round 2

Untransformed P. aeruginosa

Nir Transformed E. coli