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 .

ABSTRACT The effect of seed treatment with the actinomycetes strains EA2 and CB14, and their combination, on damping-off incidence caused by Rhizoctonia solani Kühn in Phaseolus vulgaris L. cv. Velasco largo was evaluated under greenhouse conditions. These strains were compared with Trichoderma harzianum A-34, Celest®Top 312 FS and two controls (positive and negative). Inceptisol sterile and non-sterile soil was used under a completely randomized design. The coating seeds with strains were made using 8 % cassava starch. The incidence of R. solani was determined 21 days after sowing. In non-sterile soil, the lowest incidences caused by R. solani were found with Celest®Top 312 FS, which did not significantly differ from the combination of actinomycete strains CB14 + EA2, but yes with the rest of the treatments. In the sterile soil, the lowest percentages of incidences were obtained with the combination of actinomycete strains (CB14 + EA2)

RESUMEN Se evaluó el efecto del tratamiento a las semillas con cepas de actinomicetos (EA2, CB14 y su combinación) sobre la incidencia de la marchitez de las posturas causadas por Rhizoctonia solani Kühn en Phaseolus vulgaris L. cv. Velasco largo en condiciones de casa de cultivo. Se comparó con Trichoderma harzianum A-34, Celest®Top 312 FS y dos controles (positivo y negativo). Se empleó suelo Pardo mullido medianamente lavado estéril y no estéril, bajo un diseño completamente aleatorizado. El tratamiento a la semilla fue realizado por recubrimiento, con almidón de yuca 8 % como adherente. La incidencia por R. solani se determinó a los 21 días posteriores a la siembra de las semillas. En el suelo no estéril se encontraron las menores incidencias provocadas por R. solani con el uso del Celest®Top 312 FS, el cual no difirió de la combinación de actinomicetos CB14+EA2, pero sí respecto al resto de los tratamientos. En el suelo estéril, los menores porcentajes de incidencia se obtuvieron al utilizar la combinación de cepas de actinomicetos (CB14+EA2)