Mucus-associated microbiotas among different body sites of wild tuna from the South China Sea

Abstract

The mucus-associated symbionts have profound impacts on the pathogen defense, metabolism, and development of aquatic animals. To understand the microbial structure of regional endothermic fish, a total of 52 samples from the skin, oral, gill, and hindgut of wild tuna Thunnus albacares and T. obesus were determined by 16S amplicon sequencing. The results showed the diversity and composition of microbial communities varied in the four different body sites of tunas, with a greater heterogeneity between the external surface and the gut. Phyla Proteobacteria, Firmicutes, Actinobacteria and genus Acinetobacter were found in high relative abundance in all body sites. The other abundant taxa were enriched in different body sites, such as Lactobacillus and Kocuria in the skin and Geobacillus in the gut. The core taxa interacted with each other to different degrees in the four body sites, which may be related to species’ co-evolution and microbial community stability. Finally, the correlation between biomarkers and COG functions highlighted the importance of microbial biomarkers to the host. This work firstly characterized the microbial feature in different body sites of wild tunas, providing a foundational dataset to understand the microbial role in endothermic fish and to find key microbial components beneficial to farmed tunas.

Multi-omics analysis revealed the differences in lipid metabolism of the gut between adult and juvenile yellowfin tuna (Thunnus albacares)

“…Microbiotas in the mucosal layer are appointed to represent resident bacteria ( Kashinskaya et al, 2017 ), and they showed more microbial diversity in adults than in juveniles. However, no difference was found in gut content microbial diversity and composition between juvenile and adult tunas, which was similar to our previous study in Zou et al (2023) . It is recognized that host-associated factors, such as diet, age, and species, are important factors influencing gut microbial diversity and composition ( Ou et al, 2021 ).…”

“…For tuna, a set of specialized gut bacteria may evolve specific interactions with the host. Acinetobacter , for instance, is one of the most abundant gut bacteria of tunas ( Minich et al, 2020 ; Zou et al, 2023 ), and it was significantly different in the proportion of relative abundance between adult and juvenile tunas ( Figure 1 ). This study detected a different gut mucosal microbial structure between juveniles and adults, and similar size-specific taxa differences were found in both yellowfin tuna and bigeye tuna, as described in Gadoin et al (2021) .…”

The gills and skin microbiota of five pelagic fish species from the Atlantic Ocean

“…Zou et al 2023), and has likewise been reported in the skin of farmed Thunnus maccoyii(Minich et al 2020b). Its importance for the sh skin microbiota is also indirectly shown, as the genus showed decreased relative abundance in chronically stressed sh (Cámara-…”