Accumulation of polyphosphate granules in Helicobacter pylori cells under anaerobic conditions

Helicobacter pylori is known to transform to coccoid forms which might be i nvolved in faecal-oral transmission. When the bacteria enter the intestine, they encounter anaerobiosis that is unfavourable for growth. The effect of anaerobiosis was investigated to determine whether H. pylori is viable und er such conditions. H. pylori in the late logarithmic growth phase transfor med from spiral to coccoid forms when transferred to and incubated anaerobi cally in fresh medium. Acridine orange staining indicated that the viabilit y of coccoid forms was significantly reduced, but still measurable even at day 5 or 7 of anaerobic culture. The cells retained low but significant lev els of the major sigma factor RpoD at day 5 or 7 of anaerobic culture, The cellular structures of coccoid forms contained polyphosphate granules at da y 1 and even at day 7 when incubated anaerobically, whereas only a few gran ules were observed under micro-aerobic conditions. Poor formation of polyph osphate granules in micro-aerobic cultures correlated particularly well wit h lower levels of acridine orange staining. These results suggest that acri dine orange-positive anaerobic coccoid forms are viable to a certain extent and that polyphosphate may support this viability.