Erythromycin degradation by an esterase in enzymatic membrane reactors

1 Introduction Pharmaceuticals products (PPs) and endocrine disrupting chemicals (EDCs) as well as their transformation products have been detected in almost all effluents from sewage facilities, in surface water, in groundwater, adsorbed on sediments and even in drinking water [1,2]. Ecotoxicity studies have demonstrated that pharmaceutical pollutants could affect the growth, reproduction and behavior of birds, fishes, invertebrates, plants and bacteria [3,4]. Some recently published studies report that the presence of low concentrations of antibiotics in the wastewaters may develop antibiotic resistance in the whole environment [5, 6]. As previously reported by Demarche et al. [7], the use of enzymes might be beneficial to enhance or complement conventional wastewater treatments. As far as enzymes are relatively expensive the reuse of the biocatalyst appears to be essential to ensure the economic and industrial viability of the process. Enzymatic membrane reactors appear to be an interesting alternative since they enable to couple reaction and separation [8]. In fact, in such enzymatic reactors, the substrate is continuously brought in contact with the biocatalyst, which is retained by the membrane, either freely circulating with the retentate or fixed on or within the membrane and the reaction products are recovered in the permeate. This work describes the study of erythromycin degradation by an EreB esterase in free and immobilized forms. It focuses on the comparison between 3 different enzymatic membrane reactors for erythromycin degradation by esterase EreB. In the first configuration the free biocatalyst was confined in the reaction media by a ceramic membrane. In the two other cases, the enzyme was immobilized in the membrane either covalently grafted or adsorbed. Please click Additional Files below to see the full abstract

Identification of new transformation products during enzymatic treatment of tetracycline and erythromycin antibiotics at laboratory scale by an on-line turbulent flow liquid-chromatography coupled to a high resolution mass spectrometer LTQ-Orbitrap

This work describes the formation of transformation products (TPs) by the enzymatic degradation at laboratory scale of two highly consumed antibiotics: tetracycline (Tc) and erythromycin (ERY). The analysis of the samples was carried out by a fast and simple method based on the novel configuration of the on-line turbulent flow system coupled to a hybrid linear ion trap – high resolution mass spectrometer. The method was optimized and validated for the complete analysis of ERY, Tc and their transformation products within 10 min without any other sample manipulation. Furthermore, the applicability of the on-line procedure was evaluated for 25 additional antibiotics, covering a wide range of chemical classes in different environmental waters with satisfactory quality parameters. Degradation rates obtained for Tc by laccase enzyme and ERY by EreB esterase enzyme without the presence of mediators were ∼78% and ∼50%, respectively. Concerning the identification of TPs, three suspected compounds for Tc and five of ERY have been proposed. In the case of Tc, the tentative molecular formulas with errors mass within 2 ppm have been based on the hypothesis of dehydroxylation, (bi)demethylation and oxidation of the rings A and C as major reactions. In contrast, the major TP detected for ERY has been identified as the “dehydration ERY-A”, with the same molecular formula of its parent compound. In addition, the evaluation of the antibiotic activity of the samples along the enzymatic treatments showed a decrease around 100% in both case

A novel cytochrome P450 monooxygenase from Streptomyces platensis resembles activities of human drug metabolizing P450s

Cytochrome P450 monooxygenases (P450) are versatile enzymes which play essential roles in C-source assimilation, secondary metabolism and in degradations of endo- and exogenous xenobiotics. In humans, several P450 isoforms constitute the largest part of phase I metabolizing enzymes and catalyze oxidation reactions which convert lipophilic xenobiotics, including drugs, to more water soluble species. Recombinant human P450s and microorganisms are applied in the pharmaceutical industry for the synthesis of drug metabolites for pharmacokinetics and toxicity studies. Compared to the membrane-bound eukaryotic P450s, prokaryotic ones exhibit some advantageous features, such as high stability and generally easier heterologous expression. Here, we describe a novel P450 from Streptomyces platensis DSM 40041 classified as CYP107L that efficiently converts several commercial drugs of various size and properties. This P450 was identified by screening of actinobacterial strains for amodiaquine and ritonavir metabolizing activities, followed by genome sequencing and expression of the annotated S. platensis P450s in E. coli. Performance of CYP107L in biotransformations of amodiaquine, ritonavir, amitriptyline and thioridazine resembles activities of the main human metabolizing P450s, namely CYPs 3A4, 2C8, 2C19 and 2D6. For application in the pharmaceutical industry, an E. coli whole cell biocatalyst expressing CYP107L was developed and evaluated for preparative amodiaquine metabolite production