Background: Bacterial acclimation involves cellular changes
permitting the survival of a microorganism to prolonged acid pH
exposure. The general aim of this work is to support this idea by
determining the effect of pH in the survival of the human gastric
derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild
type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which
possesses anti- Helicobacter pylori properties. Results: To assess
this aim, the exopolysaccharide production through the phenol-sulfuric
acid method was evaluated. Moreover, morphological and structural
changes by transmission and scanning electron microscopy were observed.
The bacterial survival was measured by viable count. The results showed
that the acclimated variant strain synthesized higher levels of
exopolysaccharide (690 \ub1 0.03 mg/L) more than the wild type (450
\ub1 0.12 mg/L). In addition, the acclimated variant preserved the
viable count at pH 2.6 for 48 h, whereas the wild type strain decreases
after 6 h and was non-viable at 24 h. Conclusion: The results suggest
that the acid stress acclimation of the strain L. salivarius UCO_979C-1
modified some cellular properties making this strain potentially useful
as a gastric probiotic