Selection of Autochthonous Yeasts Isolated from the Intestinal Tracts of Cobia Fish (Rachycentron canadum) with Probiotic Potential

Abstract

Some yeast strains have been proposed as probiotics to improve the health of cultured fish. Cobia is a tropical benthopelagic fish species with potential for marine aquaculture; however, one of the main limitations to its large-scale production is the high mortality of fish larvae. In this study, we evaluated the probiotic potential of autochthonous yeasts from the intestines of cobia. Thirty-nine yeast isolates were recovered from the intestinal mucosa of 37 adult healthy cobia by culture methods. Yeasts were identified by sequencing of the ITS and D1/D2 regions of the 28S rRNA gene and typed by RAPD-PCR using the M13 primer. Yeast strains with unique RAPD patterns were characterized in terms of their cell biomass production ability; anti-Vibrio, enzymatic, and hemolytic activity; biofilm production; hydrophobicity; autoaggregation; polyamine production; safety; and protection of cobia larvae against saline stress. Candida haemuloni C27 and Debaryomyces hansenii C10 and C28 were selected as potential probiotics. They did not affect the survival of larvae and showed biomass production >1 g L−1, hydrophobicity >41.47%, hemolytic activity γ, and activity in more than 8 hydrolytic enzymes. The results suggest that the selected yeast strains could be considered as potential probiotic candidates and should be evaluated in cobia larvae.

Feed Regime Slightly Modifies the Bacterial but Not the Fungal Communities in the Intestinal Mucosal Microbiota of Cobia Fish (Rachycentron canadum)

“…They are abundant in the mycobiota of rohu ( Labeo rohita ) [ 22 ] and zebrafish ( D. rerio ) [ 21 ], and they have also been identified as part of the core of several marine fish [ 14 ]. Several strains have been isolated from fish intestines using culture methods, and some have been proposed as potential probiotics for fish [ 15 , 16 , 24 , 25 ]. Saccharomyces is another genus frequently reported in aquatic environments and has also been evaluated for its probiotic potential [ 80 , 81 , 82 ].…”

“…The gDNA from each sample was amplified to verify the presence of the 16S rRNA and ITS2 regions using primers 341F (5′-CCTACGGGAGGCAGCAG-3′) and 806R (5′-GGACTACHVGGGTWTCTAAT-3′), and ITS3F (5′-GCATCGATGAAGAACGCAGC-3′) and ITS4R (5′-TCCTCCGCTTATTGATATGC-3′), respectively. The amplification reaction was performed according to [ 16 ], with slight modifications.…”

“…We previously described the dominant gut mycobiota of marine fish including salmonids ( Salmo salar , Oncorhynchus kisutch and Oncorhynchus mykiss ), croaker ( Cilus gilberti ) and yellowtail amberjack ( Seriola lalandi ) using polymerase chain reaction and temporal temperature gradient gel electrophoresis (PCR-TTGE) [ 14 ]. We also recently identified the mycobiota of cultured red cusk-eel ( Genypterus chilensis ), palm ruff ( Seriolella violacea ) [ 15 ] and cobia [ 16 ]. Sequencing the ITS, especially the ITS2 region, located between the 5.8S and 28S rRNA genes, has been highly recommended to identify fungal microorganisms [ 17 , 18 , 19 ].…”

“…Most of the microorganisms identified in fish mycobiota are yeasts belonging to the phyla Ascomycota and Basidiomycota, although filamentous fungi of Zygomycota [ 21 ], Cryptomycota, Neocallimastigomycota [ 22 ], and others have also been identified. Interestingly, some yeasts of this mycobiota have shown probiotic effects [ 15 , 16 , 24 , 25 , 26 , 27 ]. Considering the beneficial effect of some fungal commensals, further studies are needed to describe this community and understand how this mycobiota can respond to external factors such as diet.…”

Identification of new yeast strains, Candida zeylanoidesY12‐3 and Hyphopichia pseudoburtoniiY12‐1, from the intestinal tract of rainbow trout, Oncorhynchus mykiss, with potential probiotic characteristics

“…It is desirable for taxonomy, identification, and phylogenetic analysis (Sharma et al, 2023). It was successfully used to identify several fungal isolates retrieved from different fish species (Martínez et al, 2018; Reinoso et al, 2023; Taha et al, 2023). Herein, the yeast strains C. zeylanoides isolate Y12‐3 and H. pseudoburtonii isolate Y12‐1 have been identified for the first time from rainbow trout hindguts by sequencing of the ITS region.…”