RESUMO
A method was developed for the large-scale bioconversion of novel 6-deoxyerythronolide B (6-dEB) analogs into erythromycin analogs. Erythromycin biosynthesis in Saccharopolyspora erythraea proceeds via the formation of a polyketide aglycone, 6-dEB, which is subsequently glycosylated, hydroxylated and methylated to yield the antibiotic erythromycin A. A modular polyketide synthase (PKS) directs 6-dEB synthesis using a dedicated set of active sites for the condensation of each of seven propionate units. Strategies based on genetic manipulation and precursor feeding are available for the efficient generation of novel 6-dEB analogs using a plasmid-based system in Streptomyces coelicolor. 6-dEB and 13-substituted 6-dEB analogs produced in this manner were fed to S. erythraea mutants which could not produce 6-dEB, yet retained their 6-dEB modification systems, and resulted in the generation of erythromycin A and 13-substituted erythromycin A analogs. Erythromycin B, C and D analogs were observed as intermediates of the process. Dissolved oxygen, temperature, the specific aglycone feed concentration, and pH were found to be important for obtaining a high yield of erythromycin A analogs. Cultivation conditions were identified which resulted in the efficient bioconversion of 6-dEB analogs into erythromycin A analogs, which this process demonstrated at the 100 l scale.
Assuntos
Eritromicina/análogos & derivados , Eritromicina/metabolismo , Saccharopolyspora/metabolismo , Reatores Biológicos , Biotecnologia , Biotransformação , Meios de Cultura , Eritromicina/biossíntese , Eritromicina/química , Cinética , Estrutura Molecular , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Mutação , Plasmídeos/genética , Streptomyces/genética , Streptomyces/metabolismoRESUMO
Streptomyces platensis (strain NRRL 18993), a producer of dorrigocins, was shown to produce migrastatin, a cyclic congener of dorrigocin A previously reported from a different organism. Additionally a new compound isomeric to migrastatin, isomigrastatin, was also isolated and its structure was determined to be a cyclic form of dorrigocin B. Both compounds were fully characterized from MS and NMR data. Product titers of both were improved by the addition of XAD-16 resin to the fermentation medium.
Assuntos
Antibióticos Antineoplásicos/isolamento & purificação , Lactonas/isolamento & purificação , Macrolídeos , Piperidonas/isolamento & purificação , Antibióticos Antineoplásicos/química , Fermentação , Lactonas/química , Estrutura Molecular , Piperidonas/químicaRESUMO
IMPORTANCE: Cellulitis is a common and costly problem, often diagnosed in the outpatient setting. Many cutaneous conditions may clinically mimic cellulitis, but little research has been done to assess the magnitude of the problem. OBJECTIVE: To determine if obtaining dermatology consultations in the outpatient primary care setting could assist in the diagnosis of pseudocellulitic conditions and reduce the rate of unnecessary antibiotic use. DESIGN, SETTING, AND PARTICIPANTS: Nonblinded randomized clinical trial of competent adults who were diagnosed as having cellulitis by their primary care physicians (PCPs), conducted at outpatient internal medical primary care offices affiliated with a large academic medical center. INTERVENTIONS: Outpatient dermatology consultation. MAIN OUTCOMES AND MEASURES: Primary outcomes were final diagnosis, antibiotic use, and need for hospitalization. RESULTS: A total of 29 patients (12 male and 17 female) were enrolled for participation in this trial. Nine patients were randomized to continue with PCP management (control group), and 20 patients were randomized to receive a dermatology consultation (treatment group). Of the 20 patients in the dermatology consultation group, 2 (10%) were diagnosed as having cellulitis. In the control group, all 9 patients were diagnosed as having cellulitis by PCPs, but dermatologist evaluation determined that 6 (67%) of these patients had a psuedocellulitis rather than true infection. All 9 patients (100%) in the control group were treated for cellulitis with antibiotics vs 2 patients (10%) in the treatment group (P < .001). One patient in the control group was hospitalized. All patients in the treatment group reported improvement of their cutaneous condition at the 1-week follow-up examination. CONCLUSIONS AND RELEVANCE: Dermatology consultation in the primary care setting improves the diagnostic accuracy of suspected cellulitis and decreases unnecessary antibiotic use in patients with pseudocellulitic conditions. Obtaining an outpatient dermatology consultation may be a cost-effective strategy that improves quality of care. TRIAL REGISTRATION: clinicaltrials.gov Identifier:NCT01795092.