Mayo, Argel Joseph Cc. July 2022. MOLECULAR IDENTIFICATION and ANTIBACTERIAL POTENTIAL OF LACTIC ACID BACTERIA FROM SEA CUCUMBER =#/(Holothuria leucospilota): IMPLICATION TO THE GROWTH AND GUT HISTOLOGY OF NILE TILAPIA, Master of Science in Biology, Pampanga State Agricultural University, Magalang, Pampanga. Adviser: DR. JACQUELINE V. BAGUNU Lactic Acid Bacteria were screened and isolated from the gut of sea cucumber collected from the Bureau of Fisheries and Aquatic Resources - Technology Outreach Station for Marine Water in Masinloc, Zambales. Eight out of 13 isolates exhibited zones of inhibitions in a Disc Diffusion Assay. These were further tested for their antibacterial potential using the macro dilution (tube) broth method and spectrophotometric assay wherein all isolates showed a reduction in turbidity. Isolate 7 exhibited the highest reduction in bacterial growth turbidity with 9.211 compared to the control bacteria (0.394). The top five isolates with the highest reduction in growth turbidity against Aeromonas hydrophila were subjected to molecular identification and there were three Enterococcus faecium, Bacillus cereus, and Bacillus thuringiensis. These bacteria were incorporated in the feed meal of tilapia and tested for their effects on the growth performance parameters (specific gqrowth rate, survival rate, and body condition factor), gut histomorphology, and histopathology. E. faecium Strain 1, E. facium Strain 3, and B. cereus isolated from Holothuria Jleucospilota showed promising results in terms of growth rate, survival rate, body condition, and no cellular aberration in the gut, hence, recommended as additives in feed meals for Nile Tilapia. Keywords: Antibacterial potential, histomorphology, histopathology, Lactic Acid Bacteria, molecular identification Master of Science in Biology July 2022.