Date of Publication
8-2025
Document Type
Bachelor's Thesis
Degree Name
Bachelor of Science in Biology major in Medical Biology
Subject Categories
Microbiology
College
College of Science
Department/Unit
Biology
Thesis Advisor
Biena Marie S. Joaquin
Defense Panel Chair
Florabelle D. Querubin
Defense Panel Member
Florabelle D. Querubin
Raymond F. Castillo
Jandeil B. Roperos
Abstract (English)
Chanos chanos (milkfish), a key Philippine aquaculture species, produced 92.91 thousand metric tons in early 2025, representing 6.2% of the nation’s fishery output and contributing significantly to the economy over the past decade. Given milkfish’s economic importance, understanding factors that influence their health and growth is crucial. One such factor is the gut microbiota, which plays a vital role in nutrient absorption, immune system regulation, and overall product quality in aquaculture species. This study identifies and characterizes culturable bacteria present in the gut of Chanos chanos and its surrounding brackish water environment. Bacterial isolates were sourced from the gut of three milkfish individuals and their corresponding surrounding water sources. Forty-two bacterial isolates were obtained: twenty-four from the gut and eighteen from water. These isolates underwent morphological, biochemical, and genetic analyses. Nineteen gut isolates were identified as Gram-positive bacilli and five as Gram-positive cocci, while water isolates were predominantly Gram-positive bacilli, with one Gram-negative species. Biochemical testing revealed all isolates were catalase-positive, with most fermenting carbohydrates without gas production and displaying distinct indole production patterns. The 16S rRNA gene sequencing and subsequent analysis identified Bacillus and Lysinibacillus species that show potential ecological and industrial applications. Notably, the detection of opportunistic pathogens such as Enterobacter cloacae and Staphylococcus epidermidis, species not commonly associated with milkfish underscores the need for more comprehensive screening of the gut microbiota of aquatic animals and their surrounding environment. Further research is recommended to explore the other capabilities of the isolates identified in this study.
Abstract Format
html
Language
English
Format
Electronic
Keywords
Milkfish; Brackish water fishes
Recommended Citation
Del Rosario, M. L., Diwa, A. H., & Perez, C. B. (2025). Isolation and identification of culturable bacteria from the gut of brackish water-reared milkfish (Chanos chanos) and their surrounding environment. Retrieved from https://animorepository.dlsu.edu.ph/etdb_bio/113
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Embargo Period
8-16-2027
