COMPARATIVE STUDY ON GUT MICROBIOTA OF TILAPIA Oreochromis niloticus IN RECIRCULATING AQUACULTURE SYSTEM
Bacteria are found naturally in the intestine of tilapia and can be pathogenic when the environmental and crop conditions are unfavorable.The gastrointestinal microbiota plays critical roles in nutrition, development, immunity and resistance against invading pathogens, earlier studies have indicated that microbes in water may affect the fish´s microbiota. All compartments of the RAS system are in contact during cultivation, so it is relevant to know and characterize them. Understanding the integral role of the microbiota in fish is the preamble for a successful and efficient design of probiotics and prebiotics, which would allow biocontrol and biosecurity in crop.
The recirculating system consists in 12 individual's units. Each unit has a 1 m3 culture tank, a settling tank (156 L), a skimmer (5 L) a nitrification tank (339 L), and mineralization tank (89 L). The fish (O. niloticus) densities were 100 org/m3. The initial sizes tilapia was 76.88 ±3.94g, they were fed with a commercial floating feed. Samples for metagenomics analyses were taken at 18th week, the average size reached for broadcasters was from ±591 g Specific growth rate were ±1.93, survival >98% in all treatments.
Preparation of library for sequencing was done following the Illumina 16S Metagenomic Sequencing Library Preparation (Part # 15044223 Rev. B) protocol. In the well water, the Burkholderiaceae represent 76% of the total number of bacteria present, in the water of culture 18 families predominated, mainly the Burkholderiaceae (28%). In faeces are 22 bacteria families predominant, of which 13 are present in all compartments and finally in the mineralizer the Xanthomonadaceae (38%) is the most abundant (Figure 1).
