Molecular identification of culturable gut microbiota of Epinephelus morio (Red grouper) and its probiotic potential

The gut microbiota of Epinephelus morio (Valenciennes,1828) or Red grouper might be important for digestion, metabolism and health. However, little is known about the microbiota composition in this species and in captivity the microbiota could be affected by the diet composition as well as other environmental factors. In this study, the culturable gut microbiota of wild red grouper in captivity was identified through 16S rRNA gene sequencing and its potential as probiotic was studied. Six adult fish between 3-7 kg were used for intestinal content sampling using a probe. Samples were cultured in Tryptone soy and Marine Agar. Bacterial isolation was carried out in the same culture media. Subsequently, DNA extraction and amplification of the 16S rRNA gene was performed. Amplicons were purified and sent for sequencing by Sanger method. For taxonomic identification, BLASTn tool of the NCBI platform was used. Amylolytic, chitinolytic and proteolytic activity of isolates was determined using specific culture media. 22 isolates were obtained, 10 from Marine Agar culture media and 12 from TSA. Bacteria of the phyla Proteobacteria, Firmicutes and Actinobacteria were identified. The most represented species was Photobacterium damselae identified in 31.8% of the samples. Two isolates had amylolytic activity and 13 isolates had proteolytic activity. None were positive for chitinolytic activity.