IN-VITRO SCREENING OF LOCALLY ISOLATED
LACTOBACILLUS SPECIES FOR PROBIOTIC PROPERTIES
M. ASHRAF, M. ARSHAD, M. SIDDIQUE, G. MUHAMMAD1
AND H. A. KHAN
Department of Microbiology, 1Department
of Clinical Medicine and Surgery, Faculty of Veterinary Science, University of Agriculture, Faisalabad, Pakistan
Abstract
The present study was conducted to determine the
probiotic properties of locally isolated lactobacilli in-vitro conditions. For
this purpose, intestinal contents (n=20) were collected from crop, gizzard,
ileum and caecum of adult healthy chicks and conventional yogurt samples (n=20)
were procured from the local market for the isolation of lactobacilli. These
samples were mixed homogeneously in sterilized phosphate buffer saline (PBS)
separately. Samples from both sources were inoculated on deMan Rogosa and Sharpe
(MRS) agar. L. acidophilus 3, L. rhamnosus
and L. salivarius were isolated
from intestinal contents, while L.
delbrucekii ssp bulgaricus and L. paracasei ssp paracasei 1 were isolated
from yogurt samples. These lactobacilli were identified through standard API-50
CHL system and then screened for resistance against bile salt, acidic pH,
gastric transit and ability to inhibit pathogens as well as survival under
different storage temperatures. Tolerance level was found variable (P<0.05)
among all the tested species of lactobacillus. All the tested species, except
L. delbrucekii and
L. paracasei, showed good survival (P<0.05). All lactobacilli
inhibited the growth of E. coli and
Staphylococcus aureus, except
L. delbrucekii that showed
significantly (P<0.05) low antimicrobial effect. The results showed that
L. acidophilus 3, L. rhamnosus and
L. salivarius fulfilled the criteria
of in-vitro screening for probiotic
properties.