RESUMO O efeito de três culturas Streptomyces (N7, RL8 e V4) e uma mistura de Bacillus (BMix) sobre o cresimento (Peso, Tamanho) e atividade superóxido dismutase (SOD) em ostras jovens Crassostrea corteziensis e Crassostrea sikamea cultivadas artificalmente foi investigado para determinar seu potencial probiótico. Microorganismos foram adicionados à água de cultura a 1×10 6 CFU/ml uma vez por dia durante 30 dias e todas as ostras foram alimentadas diariamente com uma mistura de microalgas. Jovens C. sikamea tratados com culturas N7, RL8 e V4 tiveram ganho de peso significativo quando comparado ao grupo de controle. Jovens C. corteziensis tratados com culturas RL8 e BMix demonstraram peso significativamente mais algo que o grupo de controle. Nenhum aumento em tamanho foi observado em grupos tratados em ambas espécies. A atividade SOD foi significamente aumentada em C. sikamea treatado com RL8 e com RL8, N7 e BMix em C. corteziensis. Culturas Streptomyces RL8 e N7 surgem como agentes probióticos promissores para o cultivo de C. sikamea e C. corteziensis e podem ser úteis para outros moluscos animais marinhos invertebrados.

ABSTRACT The effect of three Streptomyces strains (N7, RL8 and V4) and a mixture of Bacillus (BMix) on the growth (Weight, Size) and superoxide dismutase activity (SOD) in hatchery-reared juvenile oysters Crassostrea corteziensis and Crassostrea sikamea was investigated to determine their probiotic potential. Microorganisms were added to culture water at 1×106 CFU/ml once a day during 30 days and all oysters fed daily a microalgae mix. Juveniles of C. sikamea treated with strains N7, RL8 and V4 had a significant weight gain compared to the control group. C. corteziensis juveniles treated with strains RL8 and BMix showed a significantly higher weight gain than the control group. No significant size increase was observed in any treated group for both oyster species. SOD activity significantly increased in C. sikamea treated with RL8 and with RL8, N7 and BMix in C. corteziensis. Streptomyces strains RL8 and N7 emerge as promising probiotic agents to cultivate C. sikamea and C. corteziensis and may also be useful to other molluscs and marine invertebrates .

Immunomodulatory action of manganese superoxide dismutase (Mn-SOD) in juvenile American white shrimp (Litopenaeus vannamei) was studied. Shrimp between 0.7 and 1.0 g were immersed in aerated β-glucan, lipopolysaccharide (LPS), fucoidan, and heat-killed Vibrio penaeicida solutions for 6 h. The enzymatic activity of Mn-SOD in entire organisms was investigated to evaluate whether different immunostimulants were able to induce antioxidant activity. The immunostimulants tested activated the immune system in juvenile shrimp and the highest antioxidant response was observed 48 h after the challenge with β-glucan, LPS, fucoidan and heat-killed V. penaeicida. The bacterin caused 3.2 times more Mn-SOD activity than the control group. Immunostimulated shrimp were challenged with live V. penaeicida on the tenth day and a second antioxidant response was observed 48 h after exposure to live pathogenic bacteria. Immunostimulated shrimp with β-glucan showed the highest Mn-SOD response (2.5 times more than the control group). This study showed the capacity of juvenile shrimp to enhance antioxidant response during a challenge with pathogenic bacteria after exposure to immunostimulants.

Se estudió la actividad inmunomoduladora de la manganeso superóxido dismutasa (MnSOD) en juveniles de camarón blanco (Litopenaeus vannamei) expuestos a diferentes inmunoestimulantes. Organismos cuyo peso varió entre 0.7 y 1.0 g fueron inmersos durante 6 h en soluciones de β-glucano, lipopolisacárido (LPS), fucoidán, y Vibrio penaeicida muerto por calor. Se determinó la actividad enzimática de la MnSOD en los organismos para evaluar si los diferentes inmunoestimulantes utilizados eran capaces de inducir actividad antioxidante. Los inmunoestimulantes probados activaron el sistema inmune de los camarones, mostrando un incremento generalizado en la respuesta antioxidante 48 h después del ensayo. El mayor incremento en la actividad de la enzima (3.2 veces superior al grupo control) se registró cuando se utilizó la bacterina. Se expusieron los camarones a V. penaeicida 10 días después de la exposición a los inmunoestimulantes, obteniendo un incremento en la actividad antioxidante de los camarones expuestos previamente a β-glucano, LPS y fucoidán. La respuesta enzimática más alta se obtuvo con los organismos estimulados con β-glucano (2.5 veces superior al control). Este estudio demostró la capacidad de los juveniles de camarón para mejorar la respuesta antioxidante después de ser expuestos a inmunoestimulantes y a una bacteria patógena.