Characterization of Lactic Acid Bacteria from the Gut of Penaeus vannamei as Potential Probiotic

Background: The present objective of the study was to isolate and characterize the gut associated culturable lactic acid bacteria (beneficial bacteria) from the gut of Penaeus vannamei for their potential application as probiotic. Methods: Penaeus vannamei (host) gut associated bacterial isolates were obtained from ten commercial brackishwater shrimp ponds (n=10) located in Kanchipuram, Chengalpattu, Tiruvallur and Villupuram districts of Tamil Nâdu, during 2021-22 to test their efficiency as indigenous gut probiotic. Twenty-five shrimps from each pond, with salinity ranging from 5 to 25 ppt, were collected for isolation of beneficial bacterial isolates. Result: Thirty lactic acid bacteria were isolated and identified from the gut of 250 Penaeus vannamei, using a 16S ribosomal DNA sequence. Six isolates viz., Pediococcus pentosaceus (ON495586), Lactiplantibacillus plantarum (ON491817), Lactococcus lactis (ON479264), Enterococcus faecium (ON478992), Enterococcus hirae (ON478991) and Enterococcus durans (ON564885) having better enzyme activity were taken and further subjected to in vitro analysis. It was found that these isolates had antibacterial activity against shrimp pathogens V. campbelli, V. harveyi and V. parahaemolyticus with zone of inhibition ranging between 12.33 to 21.00 mm; showed better growth at pH 7.0; tolerated the bile salts up to 1% concentration and endured salt concentrations up to 6.0%. In addition, above isolates demonstrated excellent auto-aggregative activity (74.45 to 91.14%) and hydrophobicity (77 to 99.93%). No antagonist activities were detected among the strains, suggesting its use as the multiple cocktail probiotic. Hence, the investigated isolates could serve as potential probiotics in shrimp aquaculture production systems.