Genome sequencing of Streptomyces aureofaciens DM-1 and analysis of 6-demethylchlortetracycline biosynthesis gene cluster / 生物工程学报

Streptomyces aureofaciens DM-1 is a high-yielding 6-demethylchlortetracycline producer. The genome sequencing of DM-1 reveals a linear chromosome containing 6 824 334 bps nucleotides with GC content of 72.6%. In this genome, a total of 6 431 open reading frames were predicted by using glimmer 3.02, Genemark and Z-Curve softwares. Twenty-eight secondary metabolite biosynthetic gene clusters were uncovered by using AntiSMASH gene prediction software, including the complete 6-demethylchlortetracycline biosynthetic gene cluster. A frame-shift mutation in methyltransferase coding region was detected, which may result in the demethylation of chlortetracycline. The complete genome sequence of S. aureofaciens DM-1 provides basic information for functional genomics studies and selection of high-yielding strains for 6-demethylchlortetracycline.

Improvement in aureofuscin production by streptomyces aureofuscus with the addition of acetate and propionate sodium / Melhoria na produção aureofuscin por Streptomyces aureofaciens com a adição de acetato e propionato de sódio

Aureofuscin is an important tetraene macrolides antibiotic produced in submerged culture by Streptomyces aureofuscus isolated from the soil in China. In the present work, the effects of the addition of precursor on cell growth and the kinetics of aureofuscin production were investigated during submerged cultivation of Str. aureofuscus. The sodium acetate and sodium propionate are more suitable precursor than alcohol, sodium butyrate, n-propanol, nbutanol. The addition of acetate and propionic sodium at a ratio of 5:1 at a total concentration of 1.5mg mL−1 after 24 h showed stimulatory effects on aureofuscin production, reaching 3.708 mg mL−1 (approximately 267% increases in aureofuscin production, compared with the control culture). Moreover , A further enhancement in aureofuscin production was achieved by cultivation in a 5-L stirred-tank bioreactor under controlled pH conditions under the above optimum condition. The optimal fermentation conditions were that 4L/min ventilatory capacity, 220r/min rotational speed, dissolves oxygen not be lower than 20%, fermentation period 84h and pH should control nearby 5.5, and the maximum yield of aureofuscin of 3.99 mg mL−1 was achieved after 84 h When the sodium acetate and sodium propionate were added as a mixture of acetate and propionate at a ratio of 5:1 and a final concentration of 1.5 mg mL−1 after 24 h cultivation.

Antitumor activity of 4-arylcoumarins from endophytic Streptomyces aureofaciens CMUAc130.

In a search for antitumor agents, we carried out a screening of 4-arylcoumarins isolated from endophytic Streptomyces aureofaciens CMUAc130, by examining their possible inhibitory effect on the growth of s.c. transplanted Lewis lung carcinoma (LLC) in BDF-1 mice by intraperitoneal (i.p.) administration. The 4-arylcoumarins showed antitumor activity with T/C values of 80.8 and 50.0% at doses of 1 and 10 mg/kg of 5,7-dimethoxy-4-p-methoxylphenylcoumarin treatment, respectively and 81.5 and 44.9% at doses of 1 and 10 mg/kg of 5,7-dimethoxy-4-phenylcoumarin treatment, respectively, compared to adriamycin, which was used a positive control, with T/C value of 55.9% at 2 mg/kg. Furthermore, we investigated the possible effects of these compounds on expression of the bcl-2 and Bax oncoproteins in A427, a human lung cancer cell lines. The cells were cultured in vitro for 24 h in RPMI 1640 with 1.5% (v/v) ethanol, 100 microg/ml 5,7-dimethoxy-4-p-methoxylphenylcoumarin or 5,7-dimethoxy-4-phenylcoumarin. Viability was determined by an MTT assay. Total protein was extracted from cell lysates and the bcl-2 and Bax oncoproteins were identified. Western blotting showed a decrease in bcl-2 and an increase in Bax in A427 cell cultured with 5,7-dimethoxy-4-p-methoxylphenylcoumarin or 5,7-dimethoxy-4-phenylcoumarin. We conclude that 5,7-dimethoxy-4-phenylcoumarin is a more potent inhibitor of cell proliferation than 5,7-dimethoxy-4-p-methoxylphenylcoumarin and has more marked effects on oncoprotein expression.

Application of element and metabolism balancing for the cultivation process with Streptomyces aureofaciens / 生物工程学报

On the base of element and metablism balancing, the mathematical model of the cultivation process with Streptomyces aureofaciens was developed, and the unknown parameters in the model were estimated with the method of nonlinear optimization. Firstly the energetic coefficient of CTC biosynthesis was gained, which was 1.8 - 2.8 mol-ATP x C-mol(-1). The macroscopic reaction rates were predicted in the process and compared with the experimental values. The results show that the model can preferably describe the relationships between several macroscopic reaction rates in the process and can supervise the optimization of CTC fermentation process theoretically.

Utilization of date-seed oil in production of tetracycline and chlortetracycline by streptomyces aureofaciens ATCC-10762

In a study of date-seed oil, 7% yield of total lipid was extractable from the seed of date palm [Phoenix dactylifera]. Thin-layer chromatography revealed that phospholipids were absent in Barni date-seed lipid, but mono-, di-, triacylglycerols, cholesterol esters and fatty acids were present. Gas chromatographic analysis was carried out on the fatty acids present in the date-seed lipid. The results revealed that lauric acid [130.61 mug/ml] was the major saturated fatty acid, while oleic acid [209.41 mug/ml] was the main unsaturated fatty acid. Myristic acid [64.7 mug/ml], palmitic acid [71.8 mug/ml], stearic acid [11.9 mug/ml] and linoleic acid [59.5 g/ml] were also present. Different date-seed lipid concentrations were used as carbon source in the fermentation medium for bioformation of tetracycline [TC] and chlortetracycline [CTC]. The high titers of TC and CTC were obtained when date-seed lipid was 30 mg/ml. Date-seed lipid was more efficient than dextrin when used as a carbon source. On utilizing date-seed lipid in the fermentation process, the residual fatty acids present in the fermented medium were determined. It was found that unsaturated fatty acids were consumed by the organism at greater percentages [49.97% oleic and 49.47% linoleic acid] than the saturated fatty acids [40.74% stearic, 39.17% myristic, 38.66% palmitic and 30.02% lauric acid]. Therefore, date-seed lipid could be used efficiently as carbon source in the formation of TC and CTC fermentation media

Demethyltetracycline biosynthesis by streptomyces aureofaciens sub-species viridulaus as influenced by medium composition

The influence of different nutritional compounds on demethyltetracycline by Streptomyces aureofaciens subspecies viridulaus was examined. Of the variety of carbon sources, nitrogen and phosphorus compounds tested; fructose, sodium nitrate and sodium dihydrogen phosphate supported the highest demethyltetracycline production. The addition of ferrous sulfate and nicotinamide [as trace element and vitamin, respectively] stimulated the biosynthesis of the antibiotic. In the majority of cases, the biomass yield ran parallel with the antibiotic production

Biosynthesis of demethyltetracycline by a strain of streptomyces

Streptomyces aureofaciens sub-species viridulaus [isolate No. MN 27] was found to produce a yellowish orange pigment. This pigment was extracted from the fermentation medium by chloroform at neutral pH [pH 7], chromatographically purified and obtained as orange powder. The purified pigmented substance exhibits a strong antimicrobial activity towards Gram positive and Gram negative bacteria [MIC =200, 50, 5, 100, 35 ug/ml against B. Subtilis, B. Megaterium, B. Cereus, Athrobacter simplex, and E. coli, respectively]. The physicochemical characteristics of the purified substance were investigated and accordingly the present antibiotic pigment was identified as a new antibiotic belonging to tetracycline group of antibiotics having indicator properties for which the name demethyltetracycline was suggested

Mutagénesis con luz ultravioleta (UV) de una cepa del género streptomyces productora de antibiótico / Ultraviolet mutagenesis of an antibiotic-producing straing of the genre streptomyces

Se aíslan 6 mutantes auxotróficos por la técnica de plaqueo por réplica después de la mutagénesis con luz ultravioleta (UV). Se señala que en la caracterización todos resultaron alterados en la vía de síntesis de la arginina. Se aíslan 4 revertantes espontáneos de 3 de los mutantes. Se informa que la aplicación del método de Kelner de difusión en agar para determinar la producción antibiótica a mutantes y revertantes y el procesamiento estadístico de los resultados obtenidos, evidenció que no existen diferencias significativas entre la cepa parental y los mutantes, pero sí entre la cepa parental y los revertantes, y produce uno de ellos, el 28-2, significativamente menos que la cepa RA-2. Se indica que el cálculo del coeficiente de variación para los mutantes evidenció una mayor estabilidad de los mutantes 20, 25, 26, y 28 en relación con la cepa parental, y el 25 es 5 veces más estable que éste