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Accumulation of polyphosphate granules in Helicobacter pylori cells under anaerobic conditions
Mutsunori Shirai, Junko Kakada, Kazuo Shibata1
1Department of Microbiology, Yamaguchi University School of Medicine, Minami-Kogushi 1-1-1, Ube City, Yamaguchi 755-8505 and *Pharmaceutical Development Research Laboratory, Tanabe Seiyaku, 2-2-50 Kawagishi, Toda, Saitama 335-0015, Japan.
Abstract:
Helicobacter pylori is known to transform to coccoid forms which might be involved 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 under such conditions. H. pylori in the late logarithmic growth phase transformed from spiral to coccoid forms when transferred to and incubated anaerobically in fresh medium. Acridine orange staining indicated that the viability of coccoid forms was significantly reduced, but still measurable even at day 5 or 7 of anaerobic culture. The cells retained low but significant levels of the major sigma factor RpoD at day 5 or 7 of anaerobic culture. The cellular structures of coccoid forms contained polyphosphate granules at day 1 and even at day 7 when incubated anaerobically, whereas only a few granules were observed under micro-aerobic conditions. Poor formation of polyphosphate granules in micro-aerobic cultures correlated particularly well with lower levels of acridine orange staining. These results suggest that acridine orange-positive anaerobic coccoid forms are viable to a certain extent and that polyphosphate may support this viability.
Insights
Helicobacter pylori transforms into viable coccoid forms under anaerobic conditions, potentially aiding fecal-oral transmission. Polyphosphate granules may support the survival of these anaerobic coccoid forms.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Environmental Microbiology
Background:
- Helicobacter pylori commonly adopts coccoid forms, a stage implicated in its fecal-oral transmission.
- The intestinal environment presents anaerobic conditions unfavorable for bacterial growth.
- Understanding H. pylori survival mechanisms in anaerobiosis is crucial for infection control.
Purpose of the Study:
- To investigate the viability and characteristics of Helicobacter pylori under anaerobic conditions.
- To determine the role of anaerobiosis in the transformation of H. pylori.
- To explore the potential role of polyphosphate granules in H. pylori survival.
Main Methods:
- H. pylori cultures were subjected to anaerobic incubation after reaching late logarithmic growth phase.
- Bacterial viability was assessed using acridine orange staining.
- The presence of the sigma factor RpoD and polyphosphate granules was analyzed.
- Comparisons were made between anaerobic and micro-aerobic culture conditions.
Main Results:
- H. pylori transformed from spiral to coccoid forms under anaerobic incubation.
- Coccoid forms exhibited reduced but measurable viability up to 7 days in anaerobic culture.
- Significant levels of the RpoD sigma factor were retained in anaerobic coccoid forms.
- Polyphosphate granules were abundant in anaerobic coccoid forms, unlike in micro-aerobic conditions.
Conclusions:
- Anaerobic coccoid forms of H. pylori demonstrate partial viability.
- Polyphosphate granules appear to play a role in supporting the survival of H. pylori under anaerobic stress.
- These findings offer insights into H. pylori transmission and persistence mechanisms.