ABSTRACT
Background: Plastic waste is a serious problem because it is difficult to degrade, thereby leading to global environment problems. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester derived from renewable resources, and it can be degraded by various enzymes produced by microorganisms. This study focused on the scale-up and evaluated the bioprocess of PLA degradation by a crude microbial enzyme produced by Actinomadura keratinilytica strain T16-1 in a 5 L stirred tank bioreactor. Results: PLA degradation after 72 h in a 5 L bioreactor by using the enzyme of the strain T16-1 under controlled pH conditions resulted in lactic acid titers (mg/L) of 16,651 mg/L and a conversion efficiency of 89% at a controlled pH of 8.0. However, the PLA degradation process inadvertently produced lactic acid as a potential inhibitor, as shown in our experiments at various concentrations of lactic acid. Therefore, the dialysis method was performed to reduce the concentration of lactic acid. The experiment with a dialysis bag achieved PLA degradation by weight loss of 99.93%, whereas the one without dialysis achieved a degradation of less than approximately 14.75%. Therefore, the dialysis method was applied to degrade a commercial PLA material (tray) with a conversion efficiency of 32%, which was 6-fold more than that without dialysis. Conclusions: This is the first report demonstrating the scale-up of PLA degradation in a 5 L bioreactor and evaluating a potential method for enhancing PLA degradation efficiency.
Subject(s)
Polyesters/metabolism , Actinomycetales/enzymology , Enzymes/metabolism , Polymers/metabolism , Biodegradation, Environmental , Lactic Acid/analysis , Bioreactors , Hydrogen-Ion ConcentrationABSTRACT
Mycetoma is a chronic, granulomatous, subcutaneous, inflammatory lesion caused by true fungi (eumycetoma) or filamentous bacteria (actinomycetoma). Mycetoma commonly affects young people between 20 and 40 years old. The most common affected site is the foot. The characteristic clinical triad is tumefaction, draining sinuses and discharging grains. We report a healthy 31-year-old male, with a 6-year history of a progressive inflammatory tumor associated with sinus tracts and granules on his left sole. Actinomycetoma was suspected. The clinical diagnosis was confirmed by microbiological and histopathological study. Polymerase chain reaction and DNA sequencing identified Actinomadura madurae. To our knowledge, this is the second case of mycetoma reported in Chile. Our report emphasizes the need to consider this diagnosis in patients with chronic granulomatous disease associated with sinus tracts, fistulas and grains.
El micetoma es una lesión subcutánea inflamatoria granulomatosa crónica causada por hongos (eumiceto-ma) o bacterias filamentosas (actinomicetoma). Afecta a adultos entre los 20-40 años y el sitio más comúnmente afectado es el pie. La tríada característica es un aumento de volumen del tejido afectado, con trayectos sinuosos y gránulos excretados. Comunicamos el caso de un hombre de 31 años, sano, con una historia de 6 años de un tumor asociado a trayectos sinuosos y gránulos en la región plantar izquierda. El diagnóstico clínico de micetoma fue confirmado mediante estudio microbiológico e histológico. La amplificación y secuenciación del AlDN bacteriano identificó Actinomadura madurae. Es el segundo caso de actinomicetoma reportado en Chile. Consideramos importante considerar este diagnóstico en pacientes con enfermedad granulomatosa crónica asociado a trayectos sinuosos, fístulas y gránulos.
Subject(s)
Adult , Humans , Male , Actinomycetales Infections/pathology , Foot Dermatoses/microbiology , Mycetoma/pathology , Actinomycetales Infections/drug therapy , Anti-Bacterial Agents/therapeutic use , Biopsy , Foot Dermatoses/pathology , Mycetoma/drug therapy , Treatment Outcome , Trimethoprim, Sulfamethoxazole Drug Combination/therapeutic useABSTRACT
Se presentan las características clínicas, microbiológicas y los resultados del tratamiento de 76 casos de micetomas observados en el período 1989-2004 en el Hospital Muñiz. Cuarenta y nueve fueron varones y 27 mujeres, con una edad promedio de 43,4 años. La mayor parte de los pacientes adquirió la infección en nuestro país, las provincias más afectadas fueron Santiago del Estero con 31 casos y el Chaco con 11; 8 enfermos procedían del exterior, 6 de Bolivia y 2 de Paraguay. El promedio de evolución de la enfermedad fue de 9,2 años. Las localizaciones más comunes fueron las de los miembros inferiores: pies 63, tobillos 3 y rodillas 2. Se comprobó compromiso óseo en 48 casos y adenomegalias en 5. Fueron identificados los siguientes agentes causales: Madurella grisea 29 casos, Actinomadura madurae 26, Scedosporium apiospermum 5, Nocardia brasiliensis 5, Acremoniun spp. 4 (Acremonium falciforme 2, Acremonium kiliense 1 y Acremonium recifei 1), Madurella mycetomatis 3, Fusarium solani 2, Nocardia asteroides y Streptomyces somaliensis 1 caso cada uno. Los tratamientos más frecuentemente utilizados fueron ketoconazol o itraconazol en los micetomas maduromicósicos y la asociación de cotrimoxazol con ciprofloxacina o amicacina en los micetomas actinomicéticos. La amputación del miembro afectado se realizó en 6 casos, 25 pacientes alcanzaron la remisión clínica completa y 34 presentaron mejorías importantes.
This work presents clinical, microbiological and outcome data collected from 76 patients with mycetomas at the Muñiz Hospital from 1989 to 2004. Forty-nine patients were male and 27 female; the mean age was 43.4 years. The majority of the patients acquired the infection in Argentina: the most affected provinces were Santiago del Estero with 31 cases, and Chaco with 11; 8 cases came from other countries (Bolivia 6 and Paraguay 2). The mean evolution of the disease was 9.2 years. The most frequently observed sites were: feet 63 cases, ankles 3, and knees 2. Forty-eight patients had bone lesions and 5, adenomegalies. The following etiological agents were identified: Madurella grisea 29 cases, Actinomadura madurae 26, Scedosporium apiospermum 5, Nocardia brasiliensis 5, Acremonium spp. 4 (Acremonium falciforme 2, Acremonium kiliense 1, Acremonium recifei 1), Madurella mycetomatis 3, Fusarium solani 2, Nocardia asteroides 1 and Streptomyces somaliensis 1. The main drugs used in the treatments were ketoconazole and itraconazole for maduromycotic mycetomas, and cotrimoxazole associated with ciprofloxacin or amikacin for actinomycetic mycetoma. Six patients had to undergo amputation, 25 cases achieved complete clinical remission and 34 showed remarkable improvement.