Antimicrobial activity of actinomycetes and characterization of actinomycin-producing strain KRG-1 isolated from Karoo, South Africa

In the present study we reported the antimicrobial activity of actinomycetes isolated from aridic soil sample collected in Karoo, South Africa. Eighty-six actinomycete strains were isolated and purified, out of them thirty-four morphologically different strains were tested for antimicrobial activity. Among 35 isolates, 10 (28.57%) showed both antibacterial and antifungal activity. The ethyl acetate extract of strain KRG-1 showed the strongest antimicrobial activity and therefore was selected for further investigation. The almost complete nucleotide sequence of the 16S rRNA gene as well as distinctive matrix-assisted laser desorption/ionization-time-of-flight/mass spectrometry (MALDI-TOF/MS) profile of whole-cell proteins acquired for strain KRG-1 led to the identification of Streptomyces antibioticus KRG-1 (GenBank accession number: KX827270). The ethyl acetate extract of KRG-1 was fractionated by HPLC method against the most suppressed bacterium Staphylococcus aureus (Newman). LC//MS analysis led to the identification of the active peak that exhibited UV-VIS maxima at 442 nm and the ESI-HRMS spectrum showing the prominent ion clusters for [M-H2O+H]+ at m/z 635.3109 and for [M+Na]+ at m/z 1269.6148. This information could be assigned to chromopeptide lactone antibiotic - actinomycin. Our results suggest that unexplored soils could be an interesting source for exploring antibacterial secondary metabolites.

Optimization of phenoxazinone synthase production by response surface methodology and its application in Congo red decolourization

Background: Enzymatic decolourization has been recently proposed as a promising and eco-friendly method for treatment of synthetic dye-contaminated wastewaters. However, the processes require large quantities of enzymes, attracting significant attention in developing efficient methods for mass production of multifunctional enzymes. Several methods such as response surface methodology (RSM) and orthogonal experiment have been applied to optimize the parameters in bioprocesses for enzyme production. Results: In the present study, a laccase-like enzyme, phenoxazinone synthase (PHS) originated from Streptomyces antibioticus was recombinantly expressed in Escherichia coli BL21 (DE3). The production of PHS in E. coli BL21 was optimized by response surface methodology based on Box-Behnken design. A full third-order polynomial model was generated by data analysis with Statistica 8.0 in which the optimal conditions for PHS production were calculated to be 1.525 mM CuSO4 and 16.096 hrs induction at temperature of 29.88ºC. The highest PHS production under optimal conditions was calculated to be 4098.51 U/l using the established model. Average PHS production obtained from actual production processes carried out under the calculated optimal conditions was 4052.00 U/l, very close to the value predicted by the model. Crude PHS was subsequently tested in Congo red decolourization which exhibited a low decolourization rate of 27% without mediator. Several mediators were found to improve PHS-catalyzed Congo red decolourization, with the highest rate of 73.89% obtained with 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) as mediator under optimized conditions of 4000 U/l PHS activity, 10 μM ABTS, 100 μM Congo red, and 8 hrs reaction time. Conclusion: Our results indicated that PHS recombinantly produced in E. coli BL21 was a prospective enzyme for decolorizing reactive dye Congo red.

Intoxicação espontânea por antibióticos ionóforos em ovinos no Rio Grande do Sul / Spontaneous poisoning by ionophores in sheep in Rio Grande do Sul, Brazil

Um surto de intoxicação espontânea por antibióticos ionóforos em ovinos da região Central do Rio Grande do Sul é descrito. Os 16 ovinos afetados estavam em campo nativo e ingeriram acidentalmente um aditivo alimentar para frangos contendo 250g/kg de narasina. Os sinais clínicos consistiam de fraqueza, incoordenação, dispnéia, secreção nasal, decúbito e morte em poucas horas. Um ovino apresentou urina escura. Macroscopicamente havia ascite, hidrotórax, edema pulmonar e palidez hepática. Discreto grau de degeneração muscular na musculatura esquelética dos membros pélvicos e torácicos foi observado histologicamente. O diagnóstico de intoxicação por narasina foi realizado com base no histórico (ingestão de aditivo alimentar contendo narasina) e nos achados clinico-patológicos.

An outbreak of spontaneous ionophore toxicity in sheep grazing in native pasture in Rio Grande do Sul state, Brazil is described. Sixteen sheep which had accidental access to a chicken feed additive containing 250g/kg of narasin were affected. Clinical signs consisted of weakness, incoordination, dyspnea, nasal discharge, recumbency, and death in a few hours. One sheep showed dark red urine. Grossly there were ascites, hydrothorax, pulmonary edema, and hepatic paleness. Discrete skeletal muscle degeneration was observed histologically in the muscles of the pelvic and thoracic limbs. The diagnostic of narasin toxicosis was based on history (ingestion of feed additive containing narasin), clinical, and pathological findings.

Production of actinomycin-D by the mutant of a new isolate of Streptomyces sindenensis / Produção de actinomicina-D por um mutante de uma nova cepa de Streptomyces sindenensis

An actinomycin-D producing strain was isolated from soil and characterized as Streptomyces sindenensis. The culture was subjected to UV irradiation and a mutant with 400 percent higher actinomycin-D production was isolated (400 mg/l-1 as compared to 80 mg/l-1 produced by the parent). Production medium was optimized and antibiotic yield with the mutant was enhanced to 850 mg/l-1 which is 963 percent higher as compared with the parent.

Uma cepa produtora de actinomicina-D foi isolada de solo e caracterizada como Streptomyces sindenensis. A cultura foi submetida à radiação UV, e um mutante capaz de produzir 400 por cento mais actinomicina-D foi isolado (400mg/L comparado a 80mg/L produzido pela cepa parental). O meio de produção do antibiótico foi otimizado e o rendimento aumentou para 850 mg/L, ou seja, 963 por cento mais alto que a cepa parental.

A chemically defined medium for production of actinomycin D by Streptomyces parvulus / A chemically defined medium for production of actinomycin D by Streptomyces parvulus

Um meio quimicamente definido composto de D (+) FRUTOSE, L (-) treonina, K2HPO4, MgSO4.7H2O, ZnSO47H2O, CaCl2.2H2o, FeSO4.7H2O e água deionizada, foi desenvolvido para maximizar a síntese de actinomicina D pelo Streptomyces parvulus DAUFPE3124. o meio proposto resultou numa concentraçäo antibiótica máxima de 133mg/L enquanto que no meio inicial a produçäo antibiótica foi baixa, näo ultrapassando 43mg/L

Corn oil favours protease production by Streptomyces viridosporus T7A

Besides of being largely used for antibiotic production, streptomyces have also been pointed out as good producers of enzymes with industrial interest such as protease. In this work, the effect of corn oil on protease production by S. virisdoporus T7A was investigated as part of a wide project for microbial protease production. Culture media contained 0.65(per cent) yeast as nitrogen source, corn oil or corn oil combined with 0.65(per cent) glucose as carbone source, plus mineral salts. In both cases, corn oil used in three differents concentrations, 0.1, 0.5 and 1(per cent) (p/V). All experiments were carried out in agitated flasks at 37§C for 105 hours. Higher protease activty (52 U/L) was obtained in medium containing 0.65(per cent) glucose and 1.0(per cent) corn oil as carbon sources. Protease activity responded positively to the increase in the medium C/N ratio, i.e., to the increment in oil concentration. Our results also suggested that corn oil favours enzyme stability during the fermentation.

Producción de oxitetraciclina por la cepa streptomyces rimosus AF-16.1 / Oxytetracycline production from streptomyces rimosus AF-16.1 strain

Se sometió la cepa Sreptomyces rimosus QBS-3 a tratamiento con acriflavina, y se obtuvo una variante con alteraciones morfológicas y fisiológicas más productora de oxitetraciclina: Sreptomyces rimosus AF-16. Se analizóel efecto de diferentes parámetros de fermentación como factores importantes en la biosíntesis de este antibiótico y se presentan resultados sobre el crecimiento del microorganismo y tiempo de producción del antibiótico. Las fermentaciones se llevaron a cabo en zaranda rotatoria a una temperatura de 30ñ 1-C. En todos los casos se determinó la actividad antibiótica al final de la fermentación de a cuerdo con la tecnica de agar difusión utilizando una cepa de Bacillus sutilis ATCC 6633 como microorganismo patrón

Producción de oxitetraciclina por la cepa streptomuces rimosus AF-16.II / Oxytetracycline producction from streptomyces rimosus AF-16.II

Mediante la cepa Streptomyces rimosus AF-16 se estudió la posible sustitución de los componentes del medio fondo por recursos nacionales. Como fuentes de carbohidrato y nitrógeno se utilizaron cabecilla de arroz y micelio del microorganismo productor, respectivamente, y se adicionaron además,carbonato de calcio, sulfato de amonio y fosfato diácido de potasio con resultados satisfactorios. El escalado a un fermentador de 1,5L produjo un incremento de la produción de oxitetraciclina por la cepa Streptomyces rimosus AF-16. Se obtuvo, por precipitación, un producto final con la calidad requerida para su empleo en el consumo animal

Incremento en la producción de eritromicina por fusión de protoplastos de Streptomyces erythreus / Increasing in the production of erythromycin by fusion of protoplasts of Streptomyces erythreus

El método de fusión de protoplastos fue usado para la obtención de recombinantes con producción antibiótica incrementada en Streptomyces erythreus productora de eritromicina. Se emplearon los mutantes morfológicos 36 UV y P-E obtenidos por luz UV y luz UV-acriflavina respectivamente, los cuales poseían marcadores de resistencia a cloranfenicol y rifampicina. Se establecen las condiciones más apropiadas para la obtención y fusión de protoplastos en estas cepas, llegándose a obtener recombinantes resistentes a ambos antibióticos a frecuencia de 0,57 %, dentro de las cuales fue seleccionado uno con incremento de 4 veces en la producción de eritromicina

Fusäo de protoplastos de Streptomyces capoamus visando a obtençäo de cepas produtoras de antibióticos "híbridos" / Protoplasts fusion of Streptomyces capoamus for obtention of strains productors of hybrid antibiotics

Pela fusäo protoplastos inativados por aquecimento a 60-C, de Streptomyces capoamus, cepa IA-M3122/182 (prototrófica, produtora de pigmento vermelho e do antibiótico antraciclínico ciclamicina) com protoplastos viáveis de Streptomyces melanochromogenes, cepa IA-M3183 (auxotrófica met- e produtora de actinomicina), foram obtidas cinco cepas com características sugestivas de recombinaçäo. Adicionalmente, foi observado que a simples produçäo e regeneraçäo de protoplastos do Streptomyces capoamus IA-M3122/182 levou à obtençäo de subculturas cuja produçäo de ciclamicina foi aumentada entre 3 e 7 vezes em relaçäo à cultura original

Sobre um complexo antibiótico do grupo das antraciclinas elaborado pelo Streptomyces violaceus / Antibiotic complex of the anthracycline compounds produced by Streptococcus violaceus

Apresenta-se o estudo taxonômico do Streptomyces violaceus isolado de uma amostra de solo proveniente da praia do Pina, Recife-PE. Relata-se também a produçäo de um antibiótico e antitumoral, um complexo antraciclínico produzido pelo referido Streptomyces. Säo apresentadas algumas informaçöes adicionais sobre as propriedades biológicas do complexo