Effect of pH soil and irrigation regimes on management of potato scab

Potato scab caused by different species of phytopathogenic Streptomyces is considered one of the main bacterial diseases of economic crop importance worldwide. Several studies are being carried out in order to control the disease, but until now, there is no efficient way to do this. Some management strategies have been investigated including application of chemical and biological products and utilization of resistant cultivars of potato but there are few reports about the impact of pH and irrigation regimes on the disease. The present study aimed to evaluate the effects of these last two factors on the incidence and severity of potato scab caused by S. scabiei, S. acidiscabies, Streptomyces sp., S. caviscabies and S. europaeiscabiei in assays at pH 4.0, 4.5, 5.0, 5.5, 6.5 and 7.5; and irrigation regimes of once a week, alternate days and daily in greenhouse conditions. The experimental design for the pH tests was randomized blocks arranged in a 5x2 factorial scheme, with 5 replications and 3x2 for the irrigation regimes with 5 replications. The pH tests showed significant differences between the treatments and pH 4,0 - 4,5 presented lower incidence and severity of the disease for the most species tested but no significant differences were observed between the irrigation regimes. The soil acidification is considered a classic strategy for management of the disease and the results obtained herein corroborated this hypothesis.

Efecto in vitro del extracto crudo de un estreptomiceto causante de sarna común de papa en Sinaloa, México / In vitro effect of the crude extract of a potato common scab streptomycete in Sinaloa, Mexico

Abstract A strain isolated from potato common scab superficial lesions in El Fuerte Valley in northern Sinaloa, Mexico, was identified by 16S rRNA and morphological methods. Moreover, the effects of the crude extract of strain V2 was evaluated on radish and potato. The isolate was similar to Streptomyces acidiscabies in its morphological properties; however, the 16S rRNA gene sequence of strain V2 was neither 100% identical to this species nor to the streptomycetes previously reported in Sinaloa, Mexico. Strain V2 did not amplify any specific PCR products for genes necl and tomA, which have been found and reported in S. acidiscabies. Strain V2 produced a PCR product for the txtAB operon, which is related to the production of thaxtomin. In vitro assays using crude thaxtomin extract and a spore suspension of the organism caused necrotic symptoms on radish and potato, which were highly virulent in potato. This study reports that Streptomyces sp. V2 has a toxigenic region (TR) that is associated with the thaxtomin gene cluster.

Resumen Se aisló una cepa de una lesión superficial de sarna común de la papa en un ejemplar procedente del Valle del Fuerte, en el norte de Sinaloa, México. La cepa fue identificada por secuenciación del gen 16S ARNr, y por sus características morfológicas. Los efectos del extracto crudo de dicha cepa, llamada V2, fue evaluado en papa y rábano. El aislado fue similar a Streptomyces acidiscabies en sus características morfológicas, pero la secuencia del gen 16S ARNr de la cepa V2 no fue 100% idéntica a la de dicha especie, ni tampoco a las de cepas identificadas dentro de este taxón previamente en Sinaloa, México. La cepa V2 no amplificó los productos específicos de PCR de los genes nec1 y tomA, los cuales sí se han reportado en S. acidiscabies. La cepa V2 amplificó el producto de PCR para del operón txtAB, relacionado con la producción de taxtomina. A través de ensayos in vitro usando un extracto crudo de taxtomina y una suspensión de esporas del organismo aislado se verificó la producción de síntomas necróticos en rábano y papa, con mayor virulencia en esta última especie. Este estudio indica que Streptomyces sp. V2 tiene una región toxigénica (TR) asociada con el cluster de genes de taxtomina.

Produção de biocompostos com atividade antimicrobiana de Streptomyces sp. ante isolados de mastite caprina / Production of biocompounds with antimicrobial activity of Streptomyces sp. Isolated in face of goat mastitis

Actinomicetos são um dos principais produtores de enzimas, vitaminas e metabólitos secundários, destacando-se o gênero Streptomyces, o qual tem uma ampla capacidade de produção de antibióticos eficazes no combate a diferentes microrganismos, entre eles o Staphylococcus sp. Em virtude dessa eficiência no combate a patógenos, o objetivo deste trabalho foi avaliar a produção de metabólitos com atividade antimicrobiana produzidos por 67 Streptomyces isolados de liquens da região amazônica, ante isolados de mastite caprina (Staphylococcus aureus) do estado de Pernambuco, Brasil. Foi utilizado um planejamento fatorial para avaliar a influência das fontes de carbono (glicose) 0%, 0,5% e 1% e de nitrogênio (farinha de soja) 1%, 2,5% e 4% na produção dos antimicrobianos, bem como das variáveis pH, biomassa e atividade antimicrobiana. Dos Streptomyces estudados, o DPUA 1566 foi o que se destacou por formação de halos de inibição entre 18 e 26mm ante os isolados de mastite caprina. Foi possível verificar que a fonte de carbono inibiu a produção de antimicrobianos quando submetidos a uma concentração de glicose de 1%; com a retirada desta, os Streptomyces apresentaram uma elevada capacidade de produção de metabólitos com atividade antimicrobiana tendo potencial para o tratamento de mastite caprina.

Actinomycetes are a leading producer of enzymes, vitamins and secondary metabolites, especially the genus Streptomyces, which have a large capacity for the production of natural antibiotics and are effective against various micro-organisms including Staphylococcus sp. Due to this efficiency in combating micro-organisms, the aim of this study was to evaluate the production of metabolites with antimicrobial activity produced by Streptomyces isolated from lichens 67 in the Amazonia, compared to isolates from goat mastitis (Staphylococcus aureus) in the state of Pernambuco, Brazil. We used a complete factorial design to evaluate the influence of concentrations of carbon sources (glucose) at 0%, 0.5% and 1% and nitrogen (soybean flour) at 1%, 2.5% and 4% in the production of antimicrobial metabolites, and the influence of the pH, microbial biomass and activity variables. Of the studied Streptomyces DPUA 1566 what stood out was the formation of inhibition halos between 18 to 26 mm compared to the isolates from goats mastitis. It was noted that the carbon source inhibited the production of antimicrobial metabolites when subjected to a glucose concentration of 1%. However, after the discontinuation, Streptomyces showed a high capacity to produce metabolites with antimicrobial activity, which has an excellent potential for the treatment of mastitis in goats.

El género Streptomyces y algunos otros géneros relacionados: aspectos morfológicos, microbiológicos, quimiotaxonómicos y moleculares: métodos de aislamiento, de cultivo y de diagnóstico / The genus streptomyces and somes other genus related: aspects morphologic, bacteriological, chemitaxonomical and molecular: methods of isolation, of cultivation and the diagnosis

El autor del presente trabajo hace una revisión y actualización sobre diversos aspectos de la biología celular y molecular del género Streptomyces y algunos otros géneros relacionados con estos microorganismos. Se presentan aspectos sobre la taxonomía, morfología, métodos de estudio: microbiológicos, quimiotaxonómicos y moleculares de los estreptomicetes. Asimismo, se revisan y actualizan los métodos de cultivo, aislamiento y de valor de diagnóstico y de identificación de estos microorganismos. Se incluyen diversas fórmulas para la preparación de medios de cultivo útiles para el aislamiento, identificación y diagnóstico de los estreptomicetes. Se presentan diversas tablas y diagramas de flujo sobre procedimientos metodológicos y de caracterización taxononómica de estos microorganismos. Se señalan las especies patógenas pertenecientes a este género de bacterias. En nueve tablas y una figura son presentados, de manera esquemática y resumida, diversos aspectos sobre morfología, taxonomía, microbiología, citoquímica y biología molecular del género Streptomyces y otros géneros relacionados

Study of the etiologic agents of mycetoma and sporotrichosis in the north of Iran [Gilan and Mazandaran provinces]

During 2 years, from March 1987 to April 1989, 600 samples of soil and plant were collected from different cities of northern provinces of Iran. Out of the six hundred samples 58 Actinomycetes, 9 Pseudallescheria boydii, 10 Sporothrix schenckii, and 4 Sporothrix schenckii-like fungi were isolated as the following: Streptomyces griseus from 31 samples [38.27%], Nocardia asteroides from 8 samples [9.87%], Actinomadura madura from 8 samples [9.87%], Streptomyces lavendulae from 6 samples [7.4/s], Nocardia autotropica from 3 samples [3.7%] Streptomyces rimosus from 1 sample[1.24%], Nocardia carnea from 1 sample [1.24%], Pseudallescheria boydii from 9 samples [11.11%],Sporothrix schenckii from 10 samples [12.34%], Spor othrix schencii-like fungi including ceratocystis sp.from 2 samples [2.48%], Doratomyces purpureofuscus from 1 sample [1.24%], and Scopulariopsis candida from 1 sample [1.24%]