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
type) and L. salivarius
UCO_979C-2 (acclimation to pH 2.6), which possesses anti- Helicobacter pylori
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 ± 0.03 mg/L) more than the wild type
(450 ± 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.
The results suggest that the acid stress acclimation of the strain L. salivarius
some cellular properties making this strain potentially useful as a gastric probiotic.