Streptomyces lunalinharesii 235 prevents the formation of a sulfate-reducing bacterial biofilm

ABSTRACT Streptomyces lunalinharesii strain 235 produces an antimicrobial substance that is active against sulfate reducing bacteria, the major bacterial group responsible for biofilm formation and biocorrosion in petroleum reservoirs. The use of this antimicrobial substance for sulfate reducing bacteria control is therefore a promising alternative to chemical biocides. In this study the antimicrobial substance did not interfere with the biofilm stability, but the sulfate reducing bacteria biofilm formation was six-fold smaller in carbon steel coupons treated with the antimicrobial substance when compared to the untreated control. A reduction in the most probable number counts of planktonic cells of sulfate reducing bacteria was observed after treatments with the sub-minimal inhibitory concentration, minimal inhibitory concentration, and supra-minimal inhibitory concentration of the antimicrobial substance. Additionally, when the treated coupons were analyzed by scanning electron microscopy, the biofilm formation was found to be substantially reduced when the supra-minimal inhibitory concentration of the antimicrobial substance was used. The coupons used for the biofilm formation had a small weight loss after antimicrobial substance treatment, but corrosion damage was not observed by scanning electron microscopy. The absence of the dsrA gene fragment in the scraped cell suspension after treatment with the supra-minimal inhibitory concentration of the antimicrobial substance suggests that Desulfovibrio alaskensis was not able to adhere to the coupons. This is the first report on an antimicrobial substance produced by Streptomyces active against sulfate reducing bacteria biofilm formation. The application of antimicrobial substance as a potential biocide for sulfate reducing bacteria growth control could be of great interest to the petroleum industry.

Optimization of Process Parameters for Improved Production of Bioactive Metabolites by Streptomyces tritolerans DAS 165T.

Aims: To optimize the process parameters for enhanced production of bioactive metabolites by Streptomyces tritolerans DAS 165T. Place and Duration of Study: Department of Botany and Microbiology, April 2012 to August 2012. Methodology: Agar well diffusion assay was employed to study the effect of environmental parameters such as incubation period, pH, temperature and salt concentration and influence of various nutrients such as carbon and nitrogen sources and minerals on the bioactive metabolite production by Streptomyces tritolerans DAS 165T.  Results: The production of antimicrobial metabolite was high when the strain was cultured for six days at 35ºC in medium (pH 7.5) with sucrose at the concentration of 2% (carbon source), soya peptone at the concentration of 1% (nitrogen source) and sodium chloride at the concentration of 5%.  Conclusion: This is the first report on the optimization of bioactive metabolite production by Streptomyces tritolerans DAS 165T. As the strain exhibited potent antimicrobial activity, it may be explored for biotechnological purposes.

Preliminary Study on Some Actinomycetes and Evaluation of Their Potential Antagonism against Fungal Pathogens.

Aims: Control of microbial pathogens by using antagonistic microorganisms is a promising alternative to chemical fungicides. The objective of the present study was to isolate and characterize soil actinomycetes and to their inhibitory activity against some fungal plant pathogens. Place and Duration of Study: National Park “El Chico”, Hidalgo State, and Laboratory of the Southeast Unit of CIATEJ, Yucatán, México, between June 2010 and May 2011. Methodology: Actinomycete species were isolated from six composite soil samples using microbiological standard procedures. All isolates were phenotypically characterized. Antagonistic isolates were selected according to the inhibitory growing of Fusarium sp. and Candida albicans. Afterwards, a new evaluation for the isolates selected was done against Helminthosporium sp., Curvularia sp., and Aspergillus niger. Actinomycetes were identified performing an analysis of the 16S rDNA gene sequence. Results: 164 actinomycete strains were characterized by morphological and biochemical features. Six of them, inhibited the growth of Fusarium sp. and C. albicans from 5 to 10 mm distance in between the actinomycete´s colony growth border of fungal or yeast. A growing reduction from 50 to 83 % in the in vitro antagonism assays was observed for Helminthosporium sp., Curvularia sp., and Aspergillus niger. Results in disc diffusion assays suggested an inhibitory growing capacity of CACIA-1.46HGO for P. capsici, this behavior could be due to the production of diffusible compounds related to secondary metabolism, hydrolytic enzymes, or both of them. Four antagonistic isolates were identified into Streptomyces genus and one as Microbacterium sp. through 16S rDNA gene sequence. Conclusion: Actinomycetes could be potentially a control tool to prevent several fungal commercial plants diseases. However, in situ isolate evaluations are suggested to be investigated.

Antibiotics produced by Streptomyces

Streptomyces is a genus of Gram-positive bacteria that grows in various environments, and its shape resembles filamentous fungi. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites, such as antifungals, antivirals, antitumorals, anti-hypertensives, immunosuppressants, and especially antibiotics. The production of most antibiotics is species specific, and these secondary metabolites are important for Streptomyces species in order to compete with other microorganisms that come in contact, even within the same genre. Despite the success of the discovery of antibiotics, and advances in the techniques of their production, infectious diseases still remain the second leading cause of death worldwide, and bacterial infections cause approximately 17 million deaths annually, affecting mainly children and the elderly. Self-medication and overuse of antibiotics is another important factor that contributes to resistance, reducing the lifetime of the antibiotic, thus causing the constant need for research and development of new antibiotics.

Taxonomy, identification and biological activities of a novel isolate of Streptomyces tendae

Various isolates of streptomycetes spp. obtained from different localities of Baghdad soils were tested for their antimicrobial activities. Five isolates showed the highest antimicrobial potentialities in the culture broth. The isolate AR1 was the most active one and thus was selected for identification. Morphological, cultural, physiological, biochemical characteristics and biological properties as well as enzymatic activities and cell wall composition suggested that the isolate is belonging to the genus Streptomyces. The 16S ribosomal DNA amplification for phylogenetic study revealed that the isolate was highly related to Streptomyces tendae [99%], so it is designated as Streptomyces tendae AR1. This new strain is capable of producing antimicrobial agent[s], which is active in vitro against Gram+ve and Gram-ve bacteria [Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus. Escherichia coli and Pseudomonas aeruginosa], yeasts [Candida albicans, Candida pseudotropicalis and Rhodotorula minuta] and fungi [Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Botrytis allii, Diplodia oryzae, Fusarium oxysporum, Helmenthosporum turcicum, Machrophomina phaseoli and Trichoderma viride]

Interaction of cultural conditions of streptomyces species, with or without their metabolites, on growth and nodulation of soybean plant

In pot experiments, the effect of treatment with plain medium of Streptomyces, containing various nitrogen sources, revealed a significant increase in fresh and dry weight of the leaves, stem and roots of soybean plants, in absence or presence of Rhizobium japonicum. The results showed more elevation due to treatment with the culture filtrates of either Streptomyces violo-chromogenes or Streptomyces glaucescens, in absence or presence of Rhizobium except treatment with culture filtrate of S. glaucescens on medium IV, in presence of Rhizobium, which induced a slight suppression in fresh and dry weight of the leaves, stem and root. In most cases, addition of culture filtrate of either organisms, growth on the test media caused an increase in number, total fresh and dry weight of root nodules of soybean plants

Strain improvement in streptomyces rimosus a producer of oxytetracycline

THE production of oxytetracycline by Streptomyces rimosus NRC 50 and NRC 5034 cultures increased 6.6 and 4.6 fold respectively with respect to the parent strain strepromyces rimosus IMRU 3558 as a result of treatment with mutagens [gamma-irradiation, U.V. light and MnC12] gamma -irradiation and U.V. light exhibited the highest mutagenic effect in increasing the productivity of the antibiotic and producing variants having a modified morphology or pigmentation

Interacción de dos hongos toxicogénicos con una cepa de streptomyces sobre el desarrollo de plantas de trigo / Interaction of 2 toxigenic fungi with a strain of streptomyces on the development of wheat seeds

Entre los microorganismos antagonistas de los suelos donde se cultivan cereales se hallan Streptomyces capaces de producir sustancias inhibidoras que pueden afectar la viabilidad y capacidad de diseminación de distintas especies de Aspergillus y Fusarium y su capacidad para producir aflatoxinas y trichotecenos. El objetivo del presente estudio fue evaluar el efecto de la interacción entre hongos toxicogénicos (Aspergillus parasiticus y Fusarium tricinctum NRRL 3299) y Streptomyces sp.antagónicos del crecimiento de tales hongos sobre el desarrollo de plantas de trigo. Se realizaron las siguientes actividades: a)inoculación de semillas de trigo, con el Streptomyces inhibidor, b) estudio del poder germinativo de las semillas de trigo, c) cultivo en cámara invernáculo de semillas inoculádas y sin inocular sembradas en tierras con y sin los hongos toxicogénicos, d) comprobación de la invasividad o ataque de los hongos mediante el rociado de espigas de plantas provenientes de suelos infectados con una suspensión de conidios de los hongos infectantes, e) determinación de las variaciones en las características botánicas de las plantas de trigo. Se pudo concluir que: 1) la presencia de hongos toxicogénicos no alteró el poder germinativo de las semillas de trigo, 2) el desarrollo vegetal, número y peso promedio de los granos de las plantas provenientes de suelos infectados con los hongos toxicogénicos fué significativamente mayor al de las plantas crecidas en tierra estéril, 3) el estudio anatómico de las plantas no puso en evidencia invasión o ataque por parte de los hongos

Biological characteristics and taxonomy of bacteria belonging to the genus Streptomyces 1 Streptomycetes with Grey-coloured aerial mycelium

A number of 16 Streptomyces strains belonging to the Grey-series were classified on the basis of the criteria recommended by the ISP. Evidences were presented for the significance of certain additional physiological and biochemical tests in completing the description of strains or species

Thermophilic Streptomyces found in sugarcane environments in Jujuy, Argentina

Se describen cepas de Streptomyces termofilicos aisladas de polvo ambiental, restos de caña de azúcar y cachaza. Todos crecieron a 50-C en 48 h dando micelio aéreo con tonos grises. Los esporos, de 0,8 -1,0 x 1,0-1,4 µm, se tiñieron con verde de malaquita. Los Streptpomyces aislados fueron identificados con los siguientes "Williams' clusters". S.chromofuscus, S. cyaneus, S. microflavus, S. antibioticus, S. basdtedii y S. violaceusniger. Los tres últimos coinciden con las especies encontradas en bagazo de caña de azúcar de otras regiones del mundo

Primeiras observaçöes sobre o antagonismo "in vitro" do streptomyces sp. IA-10493 dirigido a fungos fitopatógenos / First observations on the antagonism in vitro of Streptomyces sp IA-10493 to phytopathogenic fungi

Apresenta-se o isolamento da cultura de Streptomyces sp. IA-10493, proveniente de amostra de solo da Estaçäo Ecológica de Tapacurá-PE, resultante de um "screening de Streptomyces produtores de substâncias com atividade dirigida a fungos fitopatógenos. Mostram-se os resultados dos testes preliminares, apontando alguns fitopatógenos sensíveis à açäo antagonista do referido Streptomyces