l-Threonine production from whey and fish hydrolysate by E. coli ATCC® 21277TM.

In this work production of l-threonine by Escherichia coli ATCC® 21277™ has been studied using a mixture of alternative low-cost substrates, which are recognized to be a major pollution problem. Whey was used as the primary carbon source, whereas Red Tilapia (Oreochromis sp.) viscera hydrolysates constituted the nitrogen source. A Box-Behnken Design was used for optimizing l-threonine and biomass production, using temperature and glucose, whey, and Red Tilapia (Oreochromis sp.) viscera hydrolysate contents as factors. Results indicate that biomass production is affected by the concentration of hydrolysate and temperature. On the other hand, l-threonine production is affected by concentration of whey, hydrolysate, and temperature. In this context, it was possible to maximize l-threonine production, but with a detriment on biomass production. The optimal conditions for biomass and l-threonine maximization (after 24 h) were identified and validated experimentally, resulting in biomass and l-threonine production of 0.767 g/L and 0.406 g/L, respectively. This work has shown the technical feasibility of using whey and Red Tilapia (Oreochromis sp.) viscera hydrolysates for the production of l-threonine by E. coli ATCC® 21277TM. Finally, the complications associated to the use of these low-cost complex substrates for the production of l-threonine by E. coli, suggest that more in detail studies (i.e. at the metabolic level) are required in order to propose strategies to increase the process productivity, before its scale up. This is a first step in our long-term goal of developing a production process for i) dealing with the pollution problems caused by those wastes, and ii) strengthen the milk and fish industries which are important poles of the Colombian economy.

System metabolic engineering of Escherichia coli W for the production of 2-ketoisovalerate using unconventional feedstock.

Replacing traditional substrates in industrial bioprocesses to advance the sustainable production of chemicals is an urgent need in the context of the circular economy. However, since the limited degradability of non-conventional carbon sources often returns lower yields, effective exploitation of such substrates requires a multi-layer optimization which includes not only the provision of a suitable feedstock but the use of highly robust and metabolically versatile microbial biocatalysts. We tackled this challenge by means of systems metabolic engineering and validated Escherichia coli W as a promising cell factory for the production of the key building block chemical 2-ketoisovalerate (2-KIV) using whey as carbon source, a widely available and low-cost agro-industrial waste. First, we assessed the growth performance of Escherichia coli W on mono and disaccharides and demonstrated that using whey as carbon source enhances it significantly. Second, we searched the available literature and used metabolic modeling approaches to scrutinize the metabolic space of E. coli and explore its potential for overproduction of 2-KIV identifying as basic strategies the block of pyruvate depletion and the modulation of NAD/NADP ratio. We then used our model predictions to construct a suitable microbial chassis capable of overproducing 2-KIV with minimal genetic perturbations, i.e., deleting the pyruvate dehydrogenase and malate dehydrogenase. Finally, we used modular cloning to construct a synthetic 2-KIV pathway that was not sensitive to negative feedback, which effectively resulted in a rerouting of pyruvate towards 2-KIV. The resulting strain shows titers of up to 3.22 ± 0.07 g/L of 2-KIV and 1.40 ± 0.04 g/L of L-valine in 24 h using whey in batch cultures. Additionally, we obtained yields of up to 0.81 g 2-KIV/g substrate. The optimal microbial chassis we present here has minimal genetic modifications and is free of nutritional autotrophies to deliver high 2-KIV production rates using whey as a non-conventional substrate.

Kinetic analysis and modeling of L-valine production in fermentation batch from E. coli using glucose, lactose and whey as carbon sources.

In this study the effect of the carbon source on L-valine production kinetics using genetically modified E. coli was researched. Glucose, lactose, Whey (W) and deproteinized whey (DW) were tested as carbon sources, keeping the carbon/nitrogen (C/N) ratio constant. Biomass generation and substrate consumption were modeled with Contois and Mass Conservation models, respectively, whereas Mass Conservation Balance and Luedeking-Piret models were used for product obtaining. Results showed that L-valine production is partially associated to growth, with values of 0.485 g L-valine/(g dry cell weight.h), and a product loss effect at a specific rate (ß) of 0.019 g L-valine/(g dry cell weight.h) with W. The yield of this product increased 36 % using W concerning glucose or lactose as carbon sources. On the other hand, Mass Balance and Luedeking-Piret models adjust properly to experimental data (R2 >0.90). In conclusion whey is a promising substrate for obtaining L-valine using genetically-modified E. coli.

Queratosis seborreica en el fondo de saco de Douglas: reporte de un caso / Seborrheic keratoses in the recto-uterine pouch: Case report

Resumen ANTECEDENTES: Existen pocos reportes de neoplasias epiteliales con apariencia escamosa originadas en el cuello uterino o la vagina. Estas lesiones se clasifican, por su similitud morfológica, en lesiones similares a queratosis seborreica. Cuando ésta aparece en la mucosa de la vulva o vagina debe establecerse la diferenciación con lesiones intraepiteliales escamosas de bajo y alto grado. OBJETIVO: Describir un caso de queratosis seborreica en el saco de Douglas. CASO CLÍNICO: Paciente de 70 años, con pérdida involuntaria de orina con los esfuerzos; se le colocó una cinta suburetral para resolver este problema. Durante el procedimiento se detectó una lesión en la mucosa vaginal, a las seis del reloj, en el fondo del saco de Douglas, de 1.2 x 1 cm, color pardo y consistencia blanda. Durante el procedimiento se tomó una muestra para estudio histopatológico que se reportó como: epidermis con marcada hiperqueratosis, acantosis regular, ensanchamiento y anastomosis de las crestas con formación de perlas córneas, dermis con infiltrado inflamatorio crónico perivascular, negativo para malignidad. Se estableció el diagnóstico de queratosis seborreica hipertrófica, positiva para tinción de P16 que orientó a infección de virus del papiloma. El tratamiento fue: escisión con evolución satisfactoria y seguimiento. CONCLUSIONES: La queratosis seborreica en el fondo de saco de Douglas se reporta de manera excepcional, su comportamiento es benigno y casi siempre se asocia con tipos de virus del papiloma humano de bajo riesgo.

Abstract BACKGROUND: Thera are few repots of intraepithelial neoplasms with origins in the cervix or vagina with squamous appearance. This kind of lesions have been classified because of their morphologic similarities, in the category of "seborrheic keratoses like". When seborrheic keratoses appears in the vaginal or vulvar mucosa, it has to be differentiated from low and high grade intraepithelial squamous lesions. OBJECTIVE: To describe a case of seborrheic keratoses in the recto-uterine pouch. CLINICAL CASE: 70 years old patient, who underwent surgery for stress urinary incontinence with a sub-urethral sling. During the procedure, a lesion in the vaginal mucosa was detected, specifically in the recto-uterine pouch, of 1.2 x 1 cm length, with a light brown color and soft consistency. A specimen was taken from the lesion during the procedure for histopathological study, which reported: hyperkeratosis in the epidermis, regular acanthosis, thickening and anastomosis of the crests with formation of corneal pearls, dermis with inflammatory, chronic, perivascular infiltration, with no signs of malignancy. The diagnosis was hypertrophic seborrheic keratoses, positive for P16 stain which orients to HPV infection. The lesion was removed and the patient continued follow up with her primary care provider. CONCLUSIONS: Seborrheic keratoses in this location is uncommon, with few reports in literature. These lesions are usually benign and are associated to HPV of low risk.

Nanopartículas para materiales antibacterianos y aplicaciones del dióxido de titanio / Nanoparticles for antibacterial materials and titanium dioxide applications

La aparición constante de microorganismos multiresistentes (bacterias, virus, hongos), ha elevado el esfuerzo por la búsqueda de materiales antibacterianos, que sean efectivos para su aplicación en áreas tan diversas como la industria textil, alimentación animal, el tratamiento de aguas, industria médica, farmacéutica y cosmética. Es bien conocido que agentes antibacterianos inorgánicos tales como las nanopartículas de plata, de cobre, de óxido de zinc y de óxido de cobre, han atraído una atención especial a lo largo del tiempo, debido a su estabilidad y a que no presentan problemas de bioseguridad. Aun así, recién las nanopartículas de dióxido de titanio han venido ganando atención para aplicaciones biomédicas, dado que estas partículas se vuelven antibacteriales mediante un proceso de fotoactivación y presentan absorción de ciertas longitudes de onda que dependen de su fase inorgánica (anatasa, rutilo o brookita). No obstante, la actividad fotocatalítica del dióxido de titanio oscila en la región UV (ƛ>387nm), y ello ha representado el mayor esfuerzo en investigación, en búsqueda de conseguir que el dióxido de titanio tenga función de autodesinfección en la región de luz visible, aumentándose así sus aplicaciones en la industria biomédica. En este artículo se realizó una revisión crítica de la literatura disponible, sobre el uso de nanopartículas para materiales antibacterianos y aplicaciones del dióxido de titanio, haciéndose énfasis en el mecanismo de acción de estas partículas con sistemas biológicos y posibles modificaciones para mejorar su actividad fotocatalítica mediante la interacción con luz visible.

The constant occurrence of multiresistant microorganisms (bacteria, viruses, fungi) has increased the search for antibacterial materials that may be effective to be applied in various areas such as textile industry, animal feeding, water treatment, medical, drug and cosmetic industry. It is well known that inorganic antibacterial agents as silver, copper, zinc oxide and copper oxide nanoparticles have attired special attention in the course of time due to their stability and the absence of biosafety problems. Despite this, just recently, have the titanium dioxide nanoparticles been gaining more attention for biomedical application, since these particles become antibacterial agents through a process of photo-activation and present absorption of certain wavelengths depending on their inorganic phase (anatase, rutile or brookite). Nevertheless, the photocatalytic activity of the titanium dioxide ranges in the UV zone ((?>387nm), and this has required greater efforts in terms of research, to make the titanium dioxide have the auto-disinfection function in the visible light zone, so as to increase the number of uses in the biomedical industry. This article was aimed at making a critical literature review on the use of nanoparticles for antibacterial materials, and the applications of titanium dioxide, thus making emphasis on the mechanism of action of these particles with the biological systems and the possible changes with a view to improving its photocatalytic activity by means of the interaction with the visible light.