7 formalin-inactivated bacteria·mL -1 , for 20 minutes. Vaccinated fish groups presented higher hematocrit, number of erythrocytes and leukocytes than the non-vaccinated group. Serum agglutination titer of intraperitoneally vaccinated fish was higher on both evaluation periods for the three bacteria strains. Only on day 21 post-vaccination fish from the oral and immersion vaccination groups presented higher serum agglutination titer than the non-vaccinated fish for A. hidrophyla and E. durans. Serum antimicrobial activity in vaccinated fish was higher for P. aeroginosa and E. coli than in non-vaccinated fish on both evaluation periods. The different vaccine administration routes stimulated hematological and immunological responses in Nile tilapia 21 days post-vaccination, but intraperitoneal vaccination presented higher total number of leukocytes, lymphocytes and serum agglutination titer.
A B S T R A C TThis study evaluated the survival, post-larvae quality, and the population of bacteria in Litopenaeus vannamei after the addition of two strains of lactic-acid bacteria (2 and B6) experimentally infected by Vibrio harveyi. Fifteen hundred nauplii were distributed in 20 L capacity tanks with four replicates. The survival of control animals was lower (21%) than that of animals fed with the strains B6 (50%) and 2 (44%). Total bacterial population in the water and larvae, as well as of the Vibrio ssp. in water was not different among the treatments. No difference was observed in the population of Vibrio ssp. between the control larvae (5.5±0.5 log UFC/mL) and that fed with strain 2 (5.4±0.1 log UFC/mL). Shrimp from control and fed with strain 2 showed significantly higher bacterial population than those fed with strain B6 (1.2±0.2 log UFC/mL). It was detected the lower load of Vibrio ssp. bacteria with potential of pathogenicity after feeding with strain B6.Moreover, these larvae showed more active behavior and low number of necrosis in relation to the control group and to that fed with strain 2. R E S U M OEste trabalho avaliou a adição de duas cepas de bactérias lácticas (2 e B6) na sobrevivência, qualidade de pós-larva e na população de bactérias na larvicultura de Litopenaeus vannamei experimentalmente infectado por Vibrio harveyi. Mil e quinhentos náuplios foram distribuídos em tanques de 20 L com quatro repetições. A sobrevivência dos animais controle foi menor (21%) do que a dos alimentados com as cepas B6 (50%) e 2 (44%). Sobrevivência de misis após desafio com V. harveyi foi maior em B6 do que nos outros tratamentos. A população total de bactérias na água e nas larvas, bem como de Vibrio ssp. na água não foi diferente entre os tratamentos. Não houve diferença, também, entre a população de Vibrio ssp. em larvas do grupo controle (5,5±0,5 log UFC/mL) e larvas alimentadas com a cepa 2 (5,4±0,1 log UFC/mL). Camarões do grupo controle e alimentados com cepa 2 apresentaram maior população de bactérias do que os alimentados com cepa B6 (1,2±0,2 log UFC/mL). Foi comprovada a menor presença de bactérias entéricas com potencial de patogenicidade nos animais alimentados com a cepa B6, apresentando também comportamento mais ativo e menor número de necroses em relação ao controle e cepa 2.
-The objective of this work was to assess the time-related action of probiotic Lactobacillus plantarum in the bacterial microbiota of the digestive tract of Litopenaeus vannamei, and the relation of total haemocyte count and serum phenol oxidase activity of shrimp challenged with Vibrio harveyi. Shrimps were fed with a probiotic-supplemented diet, for eight days, then shifted to a commercial diet. Shrimps fed only with the commercial diet served as control. Evaluations were made on the 8 th day of experiment and repeated two, four, six and eight days later. Total lactic bacteria in the digestive tract was higher until the 4 th day of evaluation in the probioticsupplemented group. Vibrio spp. counts were higher in the control at days zero and two. Until the 4 th day of evaluation, the total haemocyte counts in shrimps after challenge with V. harveyi were higher in probioticsupplemented group than in control group. Significant difference was not observed in phenol oxidase activity. On the 6 th day after shifting from supplemented to control diet, all parameters were equal in both groups, suggesting that the time-related action of L. plantarum in shrimp is short.Index terms: Litopenaeus vannamei, Vibrio harveyi, total haemocyte count, lactic bacteria, phenol oxidase, probiotic. Tempo de atuação de Lactobacillus plantarum na microbiota bacteriana intestinal de camarão e sua ação como imunoestimulanteResumo -O objetivo deste trabalho foi avaliar o tempo de atuação de Lactobacillus plantarum, na microbiota bacteriana intestinal de Litopenaeus vannamei, e sua relação com a contagem total de hemócitos e a atividade da fenoloxidase após a exposição a Vibrio harveyi. Os camarões foram alimentados com dieta suplementada com probióticos por oito dias e, depois, substituída por dieta comercial. Os camarões alimentados com dieta comercial constituíram o controle. As avaliações foram realizadas no oitavo dia de experimento e repetidas dois, quatro, seis e oito dias depois. A contagem total de bactérias lácticas no intestino foi maior até o quarto dia de avaliação, no grupo alimentado com probióticos. A contagem de Vibrio spp. foi superior no grupo controle nos dias zero e dois. Até o quarto dia, a contagem total de hemócitos dos camarões após a inoculação de V. harveyi foi superior no grupo alimentado com probiótico em relação ao grupo controle. Não foi observada diferença na atividade da fenoloxidase. No sexto dia, após a substituição da dieta suplementada com probióticos por dieta controle, todos os parâmetros avaliados foram iguais nos dois grupos, o que indica que o tempo de atuação de L. plantarum em camarões é curto.Termos para indexação: Litopenaeus vannamei, Vibrio harveyi, contagem total de hemócitos, bactérias lácticas, fenoloxidase, probiótico.
-The objective of this study was to evaluate the use of a diet supplemented with Lactobacillus plantarum on performance, immunological parameters, and bacterial microbiota of the digestive tract of white leg shrimp (Litopenaeus vannamei). We used six earthen ponds (1.2 ha) stocked with 14 shrimp m −2 (3 g mean weight). Three ponds received a diet supplemented with L. plantarum and three were maintained as control. The survival and feed efficiency of shrimp fed the supplemented diet were greater than that observed in shrimp fed the control diet, with survival values of 83.02±6.12% and 74.65±9.07% and feed efficiencies of 117.97±4.45% and 104.46±7.30%, respectively. However, we observed no differences in weight gain. The intestines of shrimp fed probiotics had lower counts of Vibrio spp. and higher counts of lactic acid bacteria, compared with those of control shrimp. Diets supplemented with L. plantarum alter the intestinal bacterial microbiota of shrimp, resulting in increased survival and feed efficiency.
The aim of this study was to evaluate the pathogenicity of Vibrio alginolyticus isolated from an outbreak of sea horse Hippocampus reidi reared in the State of Santa Catarina, Brazil, by experimental infection. Sea horses with necrosis on the mouth epithelium were collected from aquaria at the Aquaculture Department, UFSC and the bacterium isolated from the mouth, liver, heart and blood in tiosulphate citrate bilesalt sucrose agar broth. The strains were identified by API 20E kit with 99.1% probability as Vibrio alginolyticus. Twelve adult sea horses (9.63 ± 2.42 g and 15.12 ± 0.87 cm) were distributed in six aquaria of 10 L capacity with aerated sea water. Fish from three aquaria were submitted to an immersion bath in a solution containing 1.0 × 10 7 CFU of V. alginolyticus/mL for 15 minutes. Fish from the other three aquaria received the same procedure without bacteria. Twenty four hours after this challenge, 100% mortality was observed in the animals infected with V. alginolyticus. No mortality was observed in non-infected fish. Hyperplasia, displacement and fusion of secondary lamellae of the gills; leukocyte infiltration and necrotic foci in the kidney; hyperplasia, sinusoidal deformation and necrotic foci in the liver were observed in histopathological analysis. The V. alginolyticus isolated in this study was pathogenic to H. reidi and constitutes an important sanitary problem to its culture.Keywords: experimental infection, vibriosis, histopathology. Isolamento e infecção experimental de Vibrio alginolyticus em cavalo-marinho,Hippocampus reidi Ginsburg, 1933 (Osteichthyes: Syngnathidae) no Brasil ResumoFoi avaliado por meio de infecção experimental a patogenicidade de Vibrio alginolyticus isolado de um surto de enfermidade em cavalo-marinho Hippocampus reidi cultivado no Estado de Santa Catarina, Brasil. Os peixes com necroses no epitélio bucal foram coletados em aquários do Departamento de Aquicultura, UFSC e as bactérias isoladas da boca, fígado, coração e sangue em meio Agar tiossulfato citrato bile sacarose. Os isolados foram identificados pelo kit API 20E como Vibrio alginolyticus com 99,1% de probabilidade. Doze peixes adultos (9,63 ± 2,42 g e 15,12 ± 0,87 cm) foram distribuídos em seis aquários de 10 L com água marinha e aeração. Peixes de três aquários foram submetidos a um banho de imersão por 15 minutos em uma solução contendo 1,0 × 10 7 UFC de V. alginolyticus/ mL. Nos outros três aquários realizou-se o mesmo procedimento sem a bactéria. Vinte e quatro horas após o desafio, 100% de mortalidade foi observada nos animais infectados com V. alginolyticus. Não houve mortalidade nos peixes não infectados. Nas análises histopatológicas, foi observado hiperplasia, deslocamento do epitélio e fusão das lamelas secundárias das brânquias; infiltração de leucócitos e necrose no rim; hiperplasia, deformação sinusoidal e necrose no fígado nos animais desafiados com V. alginolyticus. O V. alginolyticus isolado neste estudo foi patogênico para H. reidi, constituindo-se de um importante problema para seu...
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