ABSTRACT
The
mode by which Helicobacter pylori, the causative agent of most
gastric ulcers, is transmitted remains undetermined. Epidemiological
evidence suggests these organisms are waterborne; however, H.
pylori has rarely been grown from potential water sources. This
may be due to the ability of this organism to rapidly enter the viable
but nonculturable (VBNC) state. Our investigation examines the entrance
of H. pylori into this state in laboratory cultures and a
natural freshwater environment as well as the relationship between
morphology and culturability. To this end, membrane diffusion chambers
were utilized to expose the cells to the natural fluctuations of a
freshwater stream. In both the laboratory and environment, samples were
assayed for culturability using plate counts and stained using a
LIVE/DEAD BacLight assay for viability and morphological
determinations. Additionally, water samples were collected, six
environmental parameters were measured, and resuscitation conditions
were examined. H. pylori was observed to lose culturability in
the laboratory and stream, although viability was maintained. While the
results of our study agree with those of previous studies which
suggested that there is a transition in morphology from rods to cocci
as culturability is lost, the morphological distribution of cells did
not change as culturability was lost in the environment. The majority
of cells in the VBNC state in the laboratory are cocci; however, all
morphological forms were present in the environment. The results of
these studies suggest that H. pylori persists in laboratory
cultures and the environment in the VBNC state and that cells in this
state represent a public health
hazard.
Genome of a novel Sediminibacterium discovered in association with two species of freshwater stream Cyanobacteria in Southern California
