Overproduction of Erythromycin by Ultraviolet Mutagenesis and Expression of ermE Gene in Saccharopolyspora erythraea.

Erythromycin is a macrolide antibiotic with broad-spectrum activity against gram-positive bacteria that stops protein synthesis by binding to 50s ribosomal subunit. Classical and recombinant strain improvement, such as application of ultraviolet (UV) mutagenesis and selection of overproduction mutant, is the most important and convenient method in enhancement of antibiotic production. In the present study, Saccharopolyspora erythraea was mutagenized using UV lights and selection by tylosin resistance mutant to improve yield of erythromycin. In other sides, to improve the erythromycin yield in mutant, effects of various parameters such as carbon concentration and ermE gene expression were analyzed. In primary selection, high erythromycin producing strains and high erythromycin producer mutant were isolated by plaque agar, and an increase of 87% was observed in tylosin resistance mutant compared to wild-type strain. In secondary selection, a mutant strain (RHU233) with a production of 1.39 mg erythromycin per mL was isolated in fermentation process, which was 20 times more productive than the wild type. In contrast, it was found that glycerol can be used as an alternate carbon source in enhancement of erythromycin production. Comparison of ermE gene expression in mutants RHU233 high producer mutant RHU233 and wild type in Escherichia coli detected in accumulation of soluble hexahistidine-ermE was up to 45% of total cell protein after 18 h in mutants RHU233. Metal-chelation chromatography yielded 126 mg of hexahistidine-ermE per liter of culture with a purity slightly >95% in mutants RHU233. Finally, these optimized conditions could be used for the commercial production of this unique antibiotic.

Erythromycin oxidation and ERY-resistant Escherichia coli inactivation in urban wastewater by sulfate radical-based oxidation process under UV-C irradiation.

This study evaluates the feasibility of UV-C-driven advanced oxidation process induced by sulfate radicals SO4(.)- in degrading erythromycin (ERY) in secondary treated wastewater. The results revealed that 10 mg L(-1) of sodium persulfate (SPS) can result in rapid and complete antibiotic degradation within 90 min of irradiation, while ERY decay exhibited a pseudo-first-order kinetics pattern under the different experimental conditions applied. ERY degradation rate was strongly affected by the chemical composition of the aqueous matrix and it decreased in the order of: ultrapure water (kapp = 0.55 min(-1)) > bottled water (kapp = 0.26 min(-1)) > humic acid solution (kapp = 0.05 min(-1)) > wastewater effluents (kapp = 0.03 min(-1)). Inherent pH conditions (i.e. pH 8) yielded an increased ERY degradation rate, compared to that observed at pH 3 and 5. The contribution of hydroxyl and sulfate radicals (HO. and SO4(.)-) on ERY degradation was found to be ca. 37% and 63%, respectively. Seven transformation products (TPs) were tentatively elucidated during ERY oxidation, with the 14-membered lactone ring of the ERY molecule being intact in all cases. The observed phytotoxicity against the tested plant species can potentially be attributed to the dissolved effluent organic matter (dEfOM) present in wastewater effluents and its associated-oxidation products and not to the TPs generated from the oxidation of ERY. This study evidences the potential use of the UV-C/SPS process in producing a final treated effluent with lower phytotoxicity (<10%) compared to the untreated wastewater. Finally, under the optimum experimental conditions, the UV-C/SPS process resulted in total inactivation of ERY-resistant Escherichia coli within 90 min.

Manufacture and properties of erythromycin beads containing neutron-activated erbium-171.

To evaluate the effects of a neutron activation radiolabeling technique on an enteric-coated multiparticulate formulation of erythromycin, test quantities were produced under industrial pilot scale conditions. The pellets contained the stable isotope erbium oxide (Er-170), which was later converted by neutron activation into the short-lived gamma ray-emitting radionuclide, erbium-171. In vitro studies indicated that the dissolution profile, acid resistance, and enteric-coated surface of the pellets were minimally affected by the irradiation procedure. Antimicrobial potency was also unaffected, as determined by microbiological assay. Neutron activation thus appears to simplify the radiolabeling of complex pharmaceutical dosage forms for in vivo study by external gamma scintigraphy.

Screening for drug photosensitization activity by measuring the variations in oxygen consumption of Bacillus subtilis.

An original method is described for detecting the photosensitizing ability of a compound. The principle of this method is based on the analysis of variations in the consumption of oxygen by Bacillus subtilis (measured with Warburg's apparatus or an oxygenometric cell), induced by irradiation of the test compound added to the bacterial culture medium. This methodology was applied to 7 substances: 5 known photosensitizers (8-MOP, chlorpromazine, 5-fluorouracil, Vitamin A acid and benzoyl peroxide) and 2 products without any photoactive properties (aspirin and erythromycin). The comparison of results obtained with the method of photo-patch tests and the analysis of the photophysical properties of the compounds confirm the reliability, reproducibility and the quantitative nature of this method.