microorganisms. In those conditions, Pseudomonas spp. have a clear
advantage in comparison to other genera (Gill & Newton, 1977).
However, the higher psycrotrophic bacteria numbers in the absence of
nitrate/nitrite and, to a lesser extent, when the amount of these
additives was reduced by 50%, could be explained by the effect that
these compounds have on these microorganisms. Rowe, Yarbrough,
Rake, and Eagon (1979) reported that in the presence of oxygen, nitrite
inhibits active transport, oxygen uptake and oxidative phosphorylation
in Pseudomonas aeruginosa; this would take place at cell membrane
level by oxidation of ferrous to ferric iron in electron carriers, such as
cytochrome oxidase