Probiotic Characterization of Lactic Acid Bacteria Isolated from Swine Intestine

Aim: A study was conducted with the objective to isolate probiotic microorganisms from swine intestine.

Materials and Methods: In this study 63 isolates (24 caeca, 24 colon mucosal scrapings, and 15 rectal swab samples) were collected from Large White Yorkshire pigs. The isolates were inoculated and grown in de Man Rogosa Sharpe broth at 37°C with 5% CO₂ for 48 h and subjected to morphological identification. Colonies having Gram-positive rods were selected for further physiological and biochemical identification tests, which were conducted in triplicate in two runs for each of the selected isolates using a standard protocol. Probiotic properties among the identified species were determined through the implementation of several tests related with pH tolerance, bile tolerance, and antimicrobial activity.

Results: Morphological identification revealed that only 23 isolates were Gram-positive rods. Physiological tests performed on these 23 isolates further revealed that four of them did not exhibit any growth, at all conditions studied. The rest 19 isolates were, therefore, selected and subjected to biochemical tests. Six isolates were rejected because they were oxidase and nitrate reduction positive. From the 13 isolates subjected to sugar fermentation tests, speciation of only two isolates could be ascertained, one of the isolates showed characteristics for Lactobacillus acidophilus and the other for Lactobacillus plantarum. These two isolates were assessed for the strain possessing maximum probiotic property, and it was inferred that both – L. plantarum and L. acidophilus could tolerate a wide pH range (2-9), a wide bile concentration (0.05-0.3%) and revealed antimicrobial activity toward Escherichia coli, and Enterobacter spp.

Conclusion: L. plantarum and L. acidophilus were isolated from swine intestine and were found to have good probiotic properties.