Probiotic Properties of Lactic Acid Bacteria from Intensive Whiteleg Shrimp Cultivation Ponds in Bac Lieu Province, Vietnam
Quach Van Cao Thi, Nguyen Van Le, Truong Quoc TatObjective: Probiotics have significant effects on aquatic animals. Therefore, an investigation was conducted to isolate lactic acid bacteria (LAB) with probiotic properties from intensive whiteleg shrimp (Litopenaeus vannamei) farming ponds in Bac Lieu Province.
Materials and Methods: The inhibitory activity of the isolated strains was tested via the agar well diffusion method. Antibiotic susceptibility was determined using the Kirby-Bauer method. LAB isolates were identified based on their morphological and biochemical characteristics along with the 16S rRNA gene.
Results: Twenty-five LAB strains were isolated from healthy shrimp, pond water samples, and sediments. These findings demonstrated that 19 out of 25 bacterial strains were capable of inhibiting Vibrio parahaemolyticus. The four strains LSH1, LW3, LSH12, and LSH9 had the strongest inhibitory ability, with inhibition zone diameters of 21.50±0.50 mm, 17.88±0.58 mm, 18.67±0.58 mm, and 17.17±0.29 mm, respectively. LSH12 and LW3 strains were able to grow on media supplemented with 0.3% bile salt and survived at pH values ranging from 1.0 to 3.5. The results also revealed that the four strains LSH1, LW3, LSH12, and LSH9 were highly resistant to ciprofloxacin (75%), neomycin (75%), levofloxacin (50%), and streptomycin (50%). The LSH12 and LW3 strains also exhibited protease and amylase activities. 16S rRNA gene sequencing data confirmed that the LSH12 and LW3 strains were 100% similar to Lactobacillus plantarum.
Conclusion: The strains LSH12 and LW3 possess probiotic characteristics that can be applied to whiteleg shrimp farming to control V. parahaemolyticus.