Microbiota composition of yellowtail juveniles (Seriola lalandi) in a recirculation aquaculture system.

Abstract

The yellowtail (Seriola lalandi) has been farmed during the last years becoming promissory aquaculture specie. The knowledge of the intestinal microbiota has been very limited in this species; the aim of this study is to describe the bacterial populations associated to the intestinal tract of Seriola lalandi reared in Chile. The microbiota composition was analyzed at the two growth stages distinguished by weight and parameters such as SGR and FCR.Juvenile (mean initial 7.33 ± 0.30 grams) and pre-adult (81.7 ± 19.0 grams) were fed with commercial diet for 33 and 50 days respectively. The first intestinal samples at the end of Trial 1 were collected from specimens of 50 g approximately. The second samples, at the end of Trial 2, were obtained from specimens of 370 g approximately.Microbiota composition was examined by using conventional isolation in Tryptic soy agar (TSA), followed by 16S rRNA sequencing and identification. A total of 16 genera were identified; Pseudomonas, Vibrio and Staphylococcus were the predominant genera in fish of 50 grams, whereas Microbacterium and Francisella were the predominant genera in 370 g stage. The microbiotacomposition showed different assembles regarding the host sizes,the only genera shared were Bacillus and Vibrio. The knowledge of the intestinal microbiota of Seriola lalandi will be the first step to explore the microbiota management and development of probiotics, as well as, to identify the bacterial populations from healthy fish in cultured conditions.