Red grouper (Epinephelus morio) is a species of great economic importance in Yucatán, where it is the third species most captured, with a production of 5,550.36 tons in live weight, representing the 60.89% of the total national live weight of grouper fishing, with a value of 335.74 million Mexican pesos (CONAPESCA, 2020). Microbiota, the range of microorganisms that can be found in a multicellular organism can be affected by environmental factors such as pH, temperatura, and salinity with an influence in metabolism, growth, and development among other vital processes. The relationship between the microbiota and the host is known as the holobiont system. The gut microbiota has been extensively studied in several species of fish, however information regarding Epinephelus morio remains largely elusive. The objective of this study was to characterize the cultivable gut microbiota of E. morio in addition to implementing a new protocol for gut microbiota sampling in vivo.
For this purpose, 3 wild red grouper adults captured off the Yucatán Coast and taken to the facilities of the UMDI-Sisal of the Faculty of Sciences, UNAM were studied. They were anesthetized with clove oil, then a medical probe and a syringe were used to aspirate gut content from the cloaca. Samples were serially diluted in sterile physiological solution, cultured in TSA medium and marine agar plates in triplicates and incubated for 7 days at 37 °C. A total of 21 colonies were selected for further isolation in TSA medium plates incubated for 24 h at 37 °C. Isolates (n=20) were characterized using Gram stain, the BD Crystal system and 16S rRNA gene sequencing
The isolates were identified as Staphylococcus simulans (5), Staphylococcus sciuri (1), Staphylococcus haemolyticus (1), Staphylococcus saprophyticus (1), Corynebacterium diphteriae (4), Corynebacterium sp. (1) and Photobacterium damselae (7). Further studies will be performed to shed light on the roles of the E. morio gut microbiota in vital functions and health.