Francisella salimarina infection in farmed cobia (Rachycentron canadum) and dusky grouper (Epinephelus marginatus) in Brazil: A case report.

This study aimed to identify and characterize isolates of Francisella salimarina associated with an outbreak on a marine fish farm in Brazil and to analyse their genetic variability and antimicrobial susceptibility. In 2021, diseased cobias (Rachycentron canadum, n = 10) and dusky groupers (Epinephelus marginatus, n = 10) were sampled and subjected to bacteriological and pathological examinations. The isolates obtained were morphologically and biochemically characterized and identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) and 16S rRNA gene sequencing. The genetic diversity of these isolates was analysed using repetitive extragenic palindromic-polymerase chain reaction (REP-PCR). Antimicrobial susceptibility was assessed using the disk diffusion technique. Macroscopically, the fish presented skin ulcerations, ocular lesions, hepatomegaly and splenomegaly. A pleomorphic, gram-negative, catalase- and oxidase-positive bacterium was isolated from seven cobias and two groupers. The 16S rRNA gene sequences showed >99% coverage and identity with other deposited sequences of F. salimarina. The results of the biochemical analysis corresponded to these bacterial species. Histologically, granulomas were observed in the spleen, liver and heart of the cobias (n = 6), and necrotizing and fibrinous dermatitis and myositis were identified in some groupers (n = 2). The isolates exhibited the same banding pattern when REP-PCR was performed, indicating that they were clonally related. Finally, the antibiogram test, no inhibition halo was observed for amoxicillin and trimethoprim-sulfamethoxazole. To our knowledge, this is the first report of F. salimarina infection in cobias and dusky groupers.

Edwardsiella tarda in Tambaqui (Colossoma macropomum): A Pathogenicity, Antimicrobial Susceptibility, and Genetic Analysis of Brazilian Isolates.

Edwardsiella tarda is a crucial pathogenic bacterium in tropical aquaculture. This bacterium was recently isolated from tambaqui (Colossoma macropomum), a commercially important fish species in Brazil. This study assessed the antimicrobial susceptibility, pathogenicity, and genetic diversity of the tambaqui-derived E. tarda isolates. Fourteen bacterial isolates isolated from tambaqui were identified as E. tarda by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and dnaJ gene sequencing. Antimicrobial susceptibility tests were conducted against seven drugs using the disc diffusion assay. The pathogenicity test conducted by intraperitoneal injection of 2.4 × 107 colony-forming units (CFU) fish-1 of E. tarda (ED38-17) into tambaqui juveniles eventually revealed that neither clinical signs nor death were present. However, splenomegaly and whitish areas in the spleen and kidneys were observed. The histological investigation also revealed granulomatous splenitis, nephritis, and hepatitis occurring internally. Repetitive extragenic palindromic-PCR fingerprinting separated the 14 isolates into three genetic groups. The antibiogram revealed that all E. tarda isolates were wild-type (WT) to florfenicol (FLO), norfloxacin (NOR), neomycin (NEO), erythromycin (ERY), and oxytetracycline (OXY); however, some were non-wild-type to sulfamethoxazole/trimethoprim (7.1%) and amoxicillin (21.4%). Therefore, through experimental infection, E. tarda ED38-17 could induce pathogenic effects in C. macropomum. Additionally, three distinct genetic types were found, and the E. tarda isolates were WT to FLO, NOR, NEO, ERY, and OXY. These findings raise awareness of a bacteria causing unseen lesions, a pathogen that will potentially impact tambaqui aquaculture in the future.

Comparative polyphasic characterization of Weissella strains isolated from beaked whale and rainbow trout (Oncorhynchus mykiss): confirmation of Weissella ceti sp. nov. and description of the novel Weissella tructae sp. nov. isolated from farmed rainbow trout.

The weissellosis agent bacterium (WS08T = CBMAI 2730) was isolated from diseased rainbow trout (Oncorhynchus mykiss) in Brazil. The whole genome sequence of this strain was compared with the Mexican W-1 strain, also isolated from diseased rainbow trout, and with the Weissella ceti type strain CECT 7719 T (= 1119-1A-09 T = CCUG 59653 T), recovered from the beaked whale. Digital DNA-DNA hybridization pairwise analyses scored 98.7% between the Mexican W-1 and Brazilian WS08T but just 24.4% for both fish isolates compared to the W. ceti type strain CECT 7719 T. The 16S rRNA gene sequence comparisons with isolates of W. ceti, available at GenBank, were conducted. All rainbow trout-pathogenic isolates grouped close (97% bootstrap confirmation), but when this group was compared to the W. ceti type strain CECT 7719 T the similarity varied from 78.9 to 79.1%. Phenotypic assays were also conducted, and the W. ceti type strain diverged from WS08T and W-1 in the hydrolysis of aesculin, D-mannose, and potassium gluconate and in the hydrolysis of hippurate. Moreover, WS08T and W-1 showed weak growth at 5 °C whereas no growth was observed for W. ceti CECT 7719 T. The major fatty acids (> 10% total fatty acids) presented by WS08T and W-1 were summed feature 8 (C18:1 ω7c/C18:1 ω6c), summed feature 3 (C16:1 ω6c/C16:1ω7c), and C16:0. The results of phylogenetic and phenotypic analyses clearly differentiated the W. ceti CECT 7719 T type strain from the assessed pathogenic strains obtained from rainbow trout. Therefore, Weissella strains isolated from rainbow trout, here represented by strain WS08T (= CBMAI 2730), should be known as members of a novel species for which the name Weissella tructae sp. nov. is proposed.

Desenho de primers e estudo da estrutura genética em pepino do mar / Primers drawing and structure study genetics in pepino sea cucumbers

Os pepinos do mar são equinodermatas muito importantes tanto ecologicamente quanto economicamente. A exploração desse animal, principalmente de espécimes de Holothuria grisea, tem aumentado devido à recente descoberta de moléculas bioativas de interesse para a indústria farmacêutica. O objetivo desse trabalho foi identificar microssatélites que podem ser interessantes para o manejo reprodutivo e populacional dessa espécie. Para isso foi utilizado sequenciamento de nova geração seguido de identificação pelo software SSR pipeline. Foram identificados 3 microssatélites para loci diferentes, sendo um com possível aplicação na diferenciação sexual entre espécimes, além de variabilidade genética populacional bem conservada.

Sea cucumbers are very important echinodermata both ecologically and economically. The exploitation of this animal, mainly of Holothuria grisea specimens, has increased due to the recent discovery of bioactive molecules of interest for the pharmaceutical industry. The objective of this work was to identify microsatellites that may be interesting for the reproductive and population management of this species. For this, new generation sequencing was used followed by identification by the SSR pipeline software. Three microsatellites were identified for different loci, one with possible application in the sexual differentiation between specimens, in addition to well conserved population genetic variability.

Desenho de primers e estudo da estrutura genética em pepino do mar / Primers drawing and structure study genetics in pepino sea cucumbers

Os pepinos do mar são equinodermatas muito importantes tanto ecologicamente quanto economicamente. A exploração desse animal, principalmente de espécimes de Holothuria grisea, tem aumentado devido à recente descoberta de moléculas bioativas de interesse para a indústria farmacêutica. O objetivo desse trabalho foi identificar microssatélites que podem ser interessantes para o manejo reprodutivo e populacional dessa espécie. Para isso foi utilizado sequenciamento de nova geração seguido de identificação pelo software SSR pipeline. Foram identificados 3 microssatélites para loci diferentes, sendo um com possível aplicação na diferenciação sexual entre espécimes, além de variabilidade genética populacional bem conservada.(AU)

Sea cucumbers are very important echinodermata both ecologically and economically. The exploitation of this animal, mainly of Holothuria grisea specimens, has increased due to the recent discovery of bioactive molecules of interest for the pharmaceutical industry. The objective of this work was to identify microsatellites that may be interesting for the reproductive and population management of this species. For this, new generation sequencing was used followed by identification by the SSR pipeline software. Three microsatellites were identified for different loci, one with possible application in the sexual differentiation between specimens, in addition to well conserved population genetic variability.(AU)

Reprodução de peixes reofílicos nativos do Brasil: fertilização artificial e qualidade da água / Reproduction of brazilian reofilic fish: artificial fertilization and water quality

A demanda de pescado tem aumentado, sendo impulsionada pelo crescimento populacional e a busca por alimentos saudáveis indicado para o consumo humano. No entanto, a pesca predatória e a degradação do ambiente natural estão levando ao declínio das populações naturais de peixes. Nesse contexto, a expansão da piscicultura mostra-se como uma boa alternativa para contornar tais problemas. Para isso, é importante conhecer as principais técnicas reprodutivas adotadas e determinar o protocolo adequado para cada espécie. Alguns aspectos importantes devem ser considerados, como a técnica de indução à reprodução, o tipo de desova, a taxa de fertilização e eclosão dos ovos, bem como o acompanhamento do desenvolvimento embrionário e larval, além de normalidade e sobrevivência das larvas. Outros pontos importantes são o monitoramento e o controle da qualidade da água, observando parâmetros físicos e químicos, pois afetam diretamente o desenvolvimento dos organismos aquáticos. O objetivo da presente revisão foi apresentar os principais protocolos de manejo reprodutivo e parâmetros de qualidade de água na rotina de fertilização artificial de peixes reofílicos nativos do Brasil.(AU)

The fish has increased demand driven by population growth and the search for healthful foods suitable for human consumption. However, overfishing and degradation of the natural environment are leading to the decline of natural fish populations. Within context, the expansion of fish farming is a good alternative to overcome such problems. Therefore, it is important to understand the main reproductive techniques used and determine the proper protocol for each species. Some important aspects should be considered such as fish induced breeding techniques, spawning type, fertilization and hatching rate, as well as monitoring the embryonic and larval development, besides the normality and larvae survival. Other important points are the monitoring and control of water quality, observing the physical and chemical variables, as they directly affect the development of aquatic organisms. The aim of this review was to present the main protocols of reproductive management and water quality parameters in the routine of artificial fertilization of brazilian native reofilic fish.(AU)

Reprodução de peixes reofílicos nativos do Brasil: fertilização artificial e qualidade da água / Reproduction of brazilian reofilic fish: artificial fertilization and water quality

A demanda de pescado tem aumentado, sendo impulsionada pelo crescimento populacional e a busca por alimentos saudáveis indicado para o consumo humano. No entanto, a pesca predatória e a degradação do ambiente natural estão levando ao declínio das populações naturais de peixes. Nesse contexto, a expansão da piscicultura mostra-se como uma boa alternativa para contornar tais problemas. Para isso, é importante conhecer as principais técnicas reprodutivas adotadas e determinar o protocolo adequado para cada espécie. Alguns aspectos importantes devem ser considerados, como a técnica de indução à reprodução, o tipo de desova, a taxa de fertilização e eclosão dos ovos, bem como o acompanhamento do desenvolvimento embrionário e larval, além de normalidade e sobrevivência das larvas. Outros pontos importantes são o monitoramento e o controle da qualidade da água, observando parâmetros físicos e químicos, pois afetam diretamente o desenvolvimento dos organismos aquáticos. O objetivo da presente revisão foi apresentar os principais protocolos de manejo reprodutivo e parâmetros de qualidade de água na rotina de fertilização artificial de peixes reofílicos nativos do Brasil.

The fish has increased demand driven by population growth and the search for healthful foods suitable for human consumption. However, overfishing and degradation of the natural environment are leading to the decline of natural fish populations. Within context, the expansion of fish farming is a good alternative to overcome such problems. Therefore, it is important to understand the main reproductive techniques used and determine the proper protocol for each species. Some important aspects should be considered such as fish induced breeding techniques, spawning type, fertilization and hatching rate, as well as monitoring the embryonic and larval development, besides the normality and larvae survival. Other important points are the monitoring and control of water quality, observing the physical and chemical variables, as they directly affect the development of aquatic organisms. The aim of this review was to present the main protocols of reproductive management and water quality parameters in the routine of artificial fertilization of brazilian native reofilic fish.