Antagonistic activity of terrestrial <i>Streptomyces</i> sp. VITNK9 against Gram negative bacterial pathogens affecting the fish and shellfish in aquaculture

Abstract

Resumen.-Se realizaron un total de 72 aislamientos de actinomicetos morfológicamente diferentes a partir de muestras recolectadas en diferentes regiones de Vellore, Tamil Nadu, India y seleccionados por su actividad antibacteriana contra patógenos de peces y mariscos. Todos los aislamientos de actinomicetos fueron examinados para determinar la actividad antibacteriana por el método de rayas cruzadas contra los patógenos seleccionados de peces y mariscos incluyendo Aeromonas caviae, Aeromonas hydroplila, Edwardsiella tarda, Vibrio anguillarum, Vibrio harveyi. El tamizaje secundario de aislamientos antagonistas por el método de difusión de pozos conduce a la identificación de aislamiento potencial. Las condiciones de cultivo para el aislamiento potencial fue optimizado para un crecimiento y rendimiento máximo del extracto bruto de acetato de etilo (EA). El aislamiento potencial se caracterizó por la taxonomía molecular y filogenia identificándose la especie como Streptomyces y nombrado Streptomyces sp. VITNK9. La secuencia de nucleótidos 16S rDNA fue buscada a través de la base de datos GenBank y mostró 83% de similitud con Streptomyces vinaceusdrappus. El extracto EA preparado a partir de Streptomyces sp. VITNK9 mostró actividad antagonista moderada a la que se accede por la zona de formación de inhibición del crecimiento, Aeromonas caviae (15,33 mm), Aeromonas hydrophila (17,66 mm), Edwardsiella tarda (18,33 mm), Vibrio anguillarum (14,33 mm) y Vibrio harveyi (14,33 mm). El valor de CIM del extracto de EA estaba comprendido entre 0,03 y 0,125 mg mL-1. El espectro de GC-MS del extracto de acetato de etilo reveló la presencia de dos compuestos principales, pirrolo [1,2-a] pirazina-1,4-diona (56,67%) y hexahidro-3-(2-metilpropil) (27,91%), respectivamente. Los resultados del estudio sugieren que Streptomyces sp. VITNK9 es una fuente potencial de metabolitos secundarios antagónicos contra patógenos de peces y mariscos.

Actinomycetes as a promising candidate bacterial group for the health management of aquaculture systems: A review

“…48,49,119,122,141,142 Several studies have been demonstrated in fish and shellfish aquaculture using actinomycetes as antimicrobial sources. 41,59,60,68,99,101,107,111,123,128,131,133,134,137,[143][144][145][196][197][198][199][200] The different species of Actinomycetes used in aquaculture over the years have been summarized in Table 1.…”

“…have been studied and found to kill the theronts and tomonts of Ichthyophthirius multifiliis and Cryptocaryon irritans 48,49,119,122,141,142 . Several studies have been demonstrated in fish and shellfish aquaculture using actinomycetes as antimicrobial sources 41,59,60,68,99,101,107,111,123,128,131,133,134,137,143–145,196–200 …”

Draft Genome Sequence of Terrestrial Streptomyces sp. Strain VITNK9, Isolated from Vellore, Tamil Nadu, India, Exhibiting Antagonistic Activity against Fish Pathogens

“…To discover natural products possessing antagonistic activity against fish pathogens, we isolated a new actinomycete strain, Streptomyces sp. strain VITNK9, from a terrestrial soil sample from Vellore, Tamil Nadu, India, using actinomycete isolation agar (AIA) plates ( 1 , 2 ). The strain had a smooth colony surface, an earthy odor, and a spiral spore formation, including aerial mycelia and substrate hyphae penetrating through agar, morphologies typical of Streptomycetes .…”

“…The strain had a smooth colony surface, an earthy odor, and a spiral spore formation, including aerial mycelia and substrate hyphae penetrating through agar, morphologies typical of Streptomycetes . The crude extract of the strain exhibited antimicrobial activity against several fish pathogens, implying that this strain can be an important resource of bioactive metabolites ( 1 ). Further, to obtain the genomic potential of VITNK9 to synthesize bioactive compounds, its genome was sequenced.…”

“…griseus NBRC 13350 (score, 377), and Saccharopolyspora erythraea NRRL 2338 (score, 213) detected by RAST annotation ( 10 ). The MICs of the ethyl acetate (EA) crude extract of VITNK9 were found to be moderate against the following fish pathogens: Aeromonas hydrophila and Edwardsiella tarda (0.03 mg ml −1 ), Vibrio anguillarum and Vibrio harveyi (0.06 mg ml −1 , and Aeromonas caviae (0.125 mg ml −1 ) ( 1 ). Furthermore, an antiSMASH version 5.1.2 analysis ( 11 ) of the VITNK9 genome revealed 30 putative biosynthetic gene clusters (BGCs).…”