Abstract: Enterococci are important inhabitants of the animal
intestine and are widely used in probiotic products. A probiotic strain
is expected to possess several desirable properties in order to exert
beneficial effects. Therefore, the objective of this study was to
isolate, characterize and identify Enterococcus sp. from chicken cecal
and fecal samples to determine potential probiotic properties.
Enterococci were isolated from chicken ceca and feces of thirty three
clinically healthy chickens from a local farm. In vitro studies were
performed to assess antibacterial activity of the isolated LAB (using
agar well diffusion and cell free supernatant broth technique against
Salmonella enterica serotype Enteritidis), survival in acidic
conditions, resistance to bile salts, and their survival during simulated
gastric juice conditions at pH 2.5. Isolates were identified by
biochemical carbohydrate fermentation patterns using an API 50
CHL kit and API ZYM kits and by sequenced 16S rDNA. An isolate
belonging to E. faecium species exhibited inhibitory effect against S.
enteritidis. This isolate producing a clear zone as large as 10.30 mm
or greater and was able to grow in the coculture medium and at the
same time, inhibited the growth S. enteritidis. In addition, E. faecium
exhibited significant resistance under highly acidic conditions at pH
2.5 for 8 h and survived well in bile salt at 0.2% for 24 h and showing
ability to survive in the presence of simulated gastric juice at pH 2.5.
Based on these results, E. faecium isolate fulfills some of the criteria
to be considered as a probiotic strain and therefore, could be used as a
feed additive with good potential for controlling S. Enteritidis in
chickens. However, in vivo studies are needed to determine the safety
of the strain.
Abstract: In this study, three strains of Vibrio parahaemolyticus
(690, BCRC 13023 and BCRC 13025) were subjected to acid
adaptation at pH 5.5 for 90 min. The survival of acid-adapted and
non-adapted V. parahaemolyticus strains under simulated gastric
condition and their protein expression profiles were investigated.
Results showed that acid adaptation increased the survival of the test
V. parahaemolyticus strains after exposure to simulated gastric juice
(pH 3). Additionally, acid adaptation also affected the protein
expression in these V. parahaemolyticus strains. Nine proteins,
identified as atpA, atpB, DnaK, GroEL, OmpU, enolase,
fructose-bisphosphate aldolase, phosphoglycerate kinase and
triosephosphate isomerase, were induced by acid adaptation in two or
three of the test strains. These acid-adaptive proteins may play
important regulatory roles in the acid tolerance response (ATR) of V.
parahaemolyticus.