Toward the use of mixed microbial cultures for the biological production of adipic and levulinic acid

Biological synthesis of high added-value compounds like adipic acid (AA), levulinic acid (LA), or polyhydroxybutyrate (PHB) using pure culture has been separately reported. However, pure culture requires sterile conditions and the use of specific carbon sources resulting in high operating costs. Different alternatives based on the use of mixed microbial cultures (MMC) have been explored to resolve this problem. MMC have been widely reported for the production of PHB, but scarcely reported for LA production and never for AA synthesis. This work presents a novel strategy for the co-production of AA LA, and PHB using MMC. The strategy consists in selecting an MMC producer of AA, LA and PHB from an inoculum obtained from a wastewater treatment plant, which is then subjected to the feast and famine culture strategy in a sequential batch reactor, coupled with a batch reactor step to enhance the accumulation of AA and LA. The results showed that the MMC could produce a 16 ± 2, 23 ± 1 and 5 ± %1 (g compound/g volatile solids) of AA, LA and PHB, respectively, using a non-fermented residual biomass rich in pentose, namely synthetic hemicellulose hydrolysate (SHH) as the carbon source. These results contribute to generating future research to better understand and optimise the biosynthesis of these compounds by MMC.Fil: Pinto Ibieta, Fernanda. Universidad Católica de Temuco; ChileFil: Cea, Mara. Universidad de La Frontera; ChileFil: Serrano, Antonio. Universidad de Granada; EspañaFil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Cabrera, Francisco. Universidad Autónoma de Chile; ChileFil: Ciudad, Gustavo. Universidad de La Frontera; Chil

Estudio de la estabilidad de aceite comestible de girasol coloreado con pigmentos clorofílicos y con adición de oleorresina de orégano (Origanum vulgare L.) durante el almacenamiento en oscuridad.

Sunflower (Helianthus annuus L.) oil was coloured with pigments extracted from green leaves. Different amounts (0, 200, 400, 600, and 800 ppm) of oleoresin extracted from oregano (Origanum vulgare L.) as antioxidant, were added to the coloured oil. As controls, coloured oil without oleoresin (A.C.) and pure oil (A.P.) were used. The samples were stored at room temperature (10-20 ºC) in the dark for up to six months. During this time the oxidation of oleic acid, linoleic acid, peroxides index and the chlorophyll pigments were analized and the colour of the oil was determined. During the first month, only the ratio of chlorophyll to pheophytin changed, whereas all the other parameters stayed constant, independently to the amount of antioxidant added. Since among the treatments A.C. and A.P. not significant differences (p >0,05) were found, for oleic and linoleic methyl ester acids and peroxides index, it can be concluded that the edible, coloured sunflower oil shows an equivalent stability to the pure oil, when stored at darkness for three or six month. There was not observed an evident antioxidant action with the added oregano oleorresin to the coloured oil.Se estudió la estabilidad de aceite comestible de girasol (Helianthus annuus L.) de marca comercial sin antioxidantes, coloreado con pigmentos obtenidos de hojas verdes. Al aceite coloreado se adicionó oleorresina de orégano, como antioxidante, en cuatro concentraciones diferentes (200, 400, 600 y 800 ppm). Como controles, se utilizó aceite coloreado sin oleorresina (A.C.) y aceite puro (A.P.). Se almacenó en oscuridad y temperatura ambiente (10-20 ºC) por seis meses. Se evaluó la oxidación de lípidos (ésteres metílicos de ácidos oleico y linoleico e índice de peróxidos), pigmentos clorofílicos y color.El total de los pigmentos clorofilicos adicionados a las muestras de aceite comestible de girasol se mantuvo estable durante los tres primeros meses, evidenciándose sólo cambios en la proporción de clorofila a,b y feofitina a,b en el primer mes. Dado que no se encontraron diferencias significativas (p >0,05) entre los tratamientos A.P. y A.C., para ésteres metílicos de ácidos oleico y linoleico e índice de peróxidos, se podría concluir que el aceite comestible de girasol coloreado muestra una estabilidad equivalente al aceite puro, cuando es almacenado en oscuridad por tres o seis meses. No se observó un claro efecto de la acción antioxidante que tendría la oleorresina de orégano adicionada al aceite coloreado

Reaction Mechanism of the Microwave-Assisted Synthesis of 5-Hydroxymethylfurfural from Sucrose in Sugar Beet Molasses

5-hydroxymethylfurfural (HMF) stands out among the chemical products derived from biomass as a building block in the chemical industry. The conventional production of HMF is usually carried out from fructose, glucose, or other monosaccharides as feedstock, but sugar beet molasses, a by-product of the sugar industry containing sucrose (45–55%), is promising. This exploratory study used three aqueous stock solutions and one biphasic system as the sources of sucrose. The dehydration of sucrose to 5-hydroxymethylfurfural was assisted by microwave heating and subcritical water conditions. The maximum yield of HMF was 27.8 mol % for the aqueous solution of synthetic sucrose at 80 min of treatment. Although HMF yield was 7.1 mol % in the aqueous sugar beet molasses solution, it increased 2-fold after clarification (15.1 mol %) and 1.6-fold in the biphasic system (11.4 mol %). These are favorable outcomes since this is an exploratory investigation. The pseudo-first-order model fitted experimental data from the conversion of the sucrose from the stock solutions, and kinetic parameters were estimated and compared. The estimated reaction rate constant showed that inversion of sucrose is faster than fructose dehydration to HMF, but the latter reaction was the rate-determining step only for the biphasic system. The maximum partition coefficient value was four between 40 min and 60 min of reaction, calculated at room temperature. These predictions help investigators to estimate conversions and selectivity when pilot plants need to be simulated

Applications of Electrospun Nanofibers with Antioxidant Properties: A Review

Antioxidants can be encapsulated to enhance their solubility or bioavailability or to protect them from external factors. Electrospinning has proven to be an excellent option for applications in nanotechnology, as electrospun nanofibers can provide the necessary environment for antioxidant encapsulation. Forty-nine papers related to antioxidants loaded onto electrospun nanofibers were categorized and reviewed to identify applications and new trends. Medical and food fields were commonly proposed for the newly obtained composites. Among the polymers used as a matrix for the electrospinning process, synthetic poly (lactic acid) and polycaprolactone were the most widely used. In addition, natural compounds and extracts were identified as antioxidants that help to inhibit free radical and oxidative damage in tissues and foods. The most recurrent active compounds used were tannic acid (polyphenol), quercetin (flavonoid), curcumin (polyphenol), and vitamin B6 (pyridoxine). The incorporation of active compounds in nanofibers often improves their bioavailability, giving them increased stability, changing the mechanical properties of polymers, enhancing nanofiber biocompatibility, and offering novel properties for the required field. Although most of the polymers used were synthetic, natural polymers such as silk fibroin, chitosan, cellulose, pullulan, polyhydroxybutyrate, and zein have proven to be proper matrices for this purpose

Biosorption of pentachlorophenol by Anthracophyllum discolor in the form of live fungal pellets

Pentachlorophenol (PCP) is an extremely dangerous pollutant for every ecosystem. In this study we have detected how PCP concentration and pH levels can influence PCP adsorption by Anthracophyllum discolor in the form of live fungal pellets. PCP adsorption was evaluated after 24 hours in KCl 0.1 M electrolyte solution with initial PCP concentrations of 5 and 10 mg L1 and with pH values between 4 and 9 (at intervals of 0.5). Fourier Transform Infrared Spectroscopy (FTIR) was used to identify functional groups of fungal biomass that can interact with PCP. The amount of PCP that was adsorbed by A. discolor was >80% at pH values between 5 and 5.5, whatever the concentration tested. PCP adsorption significantly decreased in liquid medium of pH > 6.0. FTIR results showed that amides, alkanes, carboxylates, carboxyl and hydroxyl groups may be important to the PCP adsorption for pellets of A. discolor. Live fungal pellets of A. discolor may be used as a natural biosorbent for liquid solutions contaminated by PCP

Effects of Pyrolysis Conditions on Physicochemical Properties of Oat Hull Derived Biochar

The effects of the pyrolysis conditions in terms of temperature (400 to 600 °C), residence time (0.5 to 3.5 h), nitrogen flux (0 to 1 L/min), and temperature increase rate (1.5 to 3 °C/min) on the physicochemical properties of biochar were studied. The physicochemical properties evaluated in the biochar were specific surface area, pore volume, average pore size, total carbon content, pH, total acidity, elemental composition, and polycyclic aromatic hydrocarbons (PAHs) content. A higher specific surface area of 108.28 m2/g and a mean pore size diameter of about 2.24 nm were found when the pyrolysis was conducted at 600 °C. In general, the pH and total acidity increased with the increased pyrolysis temperature. The total PAH concentration in all of the combinations studied varied from 0.16 to 8.73 μg/kg, and only phenanthrene, pyrene, and chrysene were detected. The increased temperature seemed to decrease the PAH concentration in the biochar. Nevertheless, there was no correlation found between the PAH content and the combined evaluated parameters

Screening transesterifiable lipid accumulating bacteria from sewage sludge for biodiesel production

Sewage sludge was evaluated as high available and low cost microbial oils feedstock for biodiesel production. Samples from four different wastewater treatment plants from La Araucanía Region in Southern Chile presented total lipids content ranging between 7.7 and 12.6%, being Vilcún sewage sludge that with the highest transesterifiable lipids content of about 50% of the total extracted lipids. The most relevant identified bacteria present in sludge samples were Acinetobacter, Pseudomonas and Bacillus, being Bacillus sp. V10 the strain with the highest transesterfiable lipids content of 7.4%. Bacillus sp. V10 was cultured using urban wastewater supplemented with glucose to achieve nitrogen depleted medium and using milk processing wastewater as a low-cost carbon source. Bacillus sp. V10 lipid profile indicates that low degree unsaturated long chain fatty acids such as C18:1 may account for approximately 50% of the lipids content, indicating its suitability to be used as raw material for biodiesel production