Breeding Asian seabass to increase survival against big belly disease and growth

Parasalinivibrio latis gen. nov., sp. nov., isolated from the distal gut of healthy farmed Asian Seabass (Lates calcarifer)

Asian Seabass (Lates calcarifer) is widely farmed as a sustainable source of protein for countries in the tropical Indo-West Pacific region. However, microbial species of the gut microbiome of healthy Asian Seabass remain largely uncharacterized and uncultured. Here, we analysed the microbial composition along the gastrointestinal tract of a farmed healthy Asian Seabass. We used different cultivation approaches to obtain isolates from the seabass intestinal tract and describe the isolation and characterization of a novel strain, TLL-SE01T. Analysis of the strain's 16S rRNA gene indicates that the strain belongs to the family Vibrionaceae with Photobacterium damselae as its closest relative, albeit sharing only 94.8% (aligned region 1553 bp) nucleotide identity. Comparative genomic analysis with all validly published Vibrionaceae species with available genomes revealed average nucleotide identity (ANI) and DNA-DNA hybridisation (DDH) values of around 70% and 24% respectively to strain TLL-SE01T, which are well below proposed thresholds for species delineation (ANI, 95-96%; DDH, 70%). The alignment fraction and ANI genus demarcation boundaries for all genera in the Vibrionaceae family were determined for which strain TLL-SE01T is well below the calculated values, indicating that it belongs to a novel genus. Single- and core-gene phylogenetic analysis places strain TLL-SE01T in a monophyletic clade, further supporting its designation to a novel genus. Phenotypic comparison between strain TLL-SE01T and its close relatives indicated additional differences, such as growth response at different salt concentrations and different metabolic capabilities. Based on genotypic, phylogenetic and phenotypic differences to other Vibrionaceae species, we propose a novel species in a new genus, Parasalinivibrio latis gen. nov. sp. nov. and strain TLL-SE01T (= BCRC 81435T = JCM 36283T) as the type strain.

Bacterial diseases of Asian sea bass (Lates calcarifer): A review for health management strategies and future aquaculture sustainability

The advent of aquaculture has been one of the most significant shifts in world food supply during the last century. Aquaculture has rapidly expanded and become a global food industry, spurred by population expansion, increased seafood consumption, and decreased captured fisheries. Nonetheless, the exponential growth of aquaculture has emerged as a significant contributor to anthropogenic changes. Unexpectedly, the result has focused in the emergence and spread of new diseases. The Asian sea bass (Lates calcarifer) is an economically important species in aquaculture, contributing significantly to the global seafood market. However, bacterial diseases have emerged as a major concern, affecting both wild and cultured populations of this species. The most prevalent bacterial pathogens are streptococcus, vibriosis, nocardiosis, tenacibaculosis, and pot-belly disease. Therefore, this review aims to comprehensively analyze both emerging and non-emerging bacterial diseases affecting L. calcarifer and explore potential management approaches for their control. Through an extensive literature survey and critical evaluation of research findings, this review highlights the current understanding of bacterial diseases in L. calcarifer and proposes strategies for better disease management. In addition, this review looks at the rise and characteristics of aquaculture, the major bacterial pathogens of L. calcarifer and their effects, and the specific attributes of disease emergence in an aquatic rather than terrestrial context. It also considers the potential for future disease emergence in L. calcarifer due to aquaculture expansion and climate changes.