Nitrite accumulation during anaerobic nitrate reduction by binary suspensions of bacteria isolated from the achlorhydric stomach.

Binary suspensions of bacteria isolated from the gastric juice of achlorhydric patients were used to determine conditions which favour nitrite accumulation during nitrate reduction. Suspensions of Veillonella parvula and Haemophilus parainfluenzae accumulated nitrite during nitrate reduction in the absence of nitrite-reducing Neisseria subflava or Streptococcus sanguis. The maximum concentration of nitrite that transiently accumulated decreased predictably as the ratio of nitrite-removing bacteria to nitrite-accumulating bacteria increased. This ratio, but more importantly the bacterial density, determined the duration of nitrite accumulation. These results are correlated with the previously reported tendency of nitrite to accumulate in the gastric juice of hypogammaglobulinaemic and pernicious anaemic patients, and with the extremely high incidence of gastric cancer in the two groups.