The external NO2- concentration is 1-2 micromolar. I don't know what the periplasmic concentration would be, possibly higher. The timescale I am interested in is 1-24 hours. The bacteria I am looking at are beta proteobacteria, specifically ammonia oxidizers.
The external pH is about neutral, so almost all the NO2- is in the anionic form (not HNO2). I gather that NO2- is probably small enough to pass through porins, but I do not know if the outer cell membrane would be a critical barrier or not over the timescale or concentrations I am interested in.
Does anyone know how I might figure this out? Thanks!