Ultrasound mediated enzymatic hydrolysis of cellulose and carboxymethyl cellulose

A recombinant Trichoderma reesei cellulase was used for the ultrasound‐mediated hydrolysis of soluble carboxymethyl cellulose (CMC) and insoluble cellulose of various particle sizes. The hydrolysis was carried out at low intensity sonication (2.4–11.8 W cm−2 sonication power at the tip of the sonotrode) using 10, 20, and 40% duty cycles. [A duty cycle of 10%, for example, was obtained by sonicating for 1 s followed by a rest period (no sonication) of 9 s.] The reaction pH and temperature were always 4.8 and 50°C, respectively. In all cases, sonication enhanced the rate of hydrolysis relative to nonsonicated controls. The hydrolysis of CMC was characterized by Michaelis‐Menten kinetics. The Michaelis‐Menten parameter of the maximum reaction rate Vmax was enhanced by sonication relative to controls, but the value of the saturation constant Km was reduced. The optimal sonication conditions were found to be a 10% duty cycle and a power intensity of 11.8 W cm−2. Under these conditions, the maximum rate of hydrolysis of soluble CMC was nearly double relative to control. In the hydrolysis of cellulose, an increasing particle size reduced the rate of hydrolysis. At any fixed particle size, sonication at a 10% duty cycle and 11.8 W cm−2 power intensity improved the rate of hydrolysis relative to control. Under the above mentioned optimal sonication conditions, the enzyme lost about 20% of its initial activity in 20 min. Sonication was useful in accelerating the enzyme catalyzed saccharification of cellulose

Concentración de cultivos de microalgas por un proceso de eliminación osmótica del medio utilizando disoluciones de glicerol

Número de publicación: ES2545829 A1 (15.09.2015) También publicado como: ES2545829 B2 (15.01.2016) Número de Solicitud: Consulta de Expedientes OEPM (C.E.O.) P201400232 (12.03.2014)La presente invención consiste en concentrar cultivos de microalgas mediante un proceso económico y de bajo consumo energético pudiendo reaprovechar el glicerol residual de la síntesis de biodiesel. La disolución de glicerol constituye la solución osmótica, que se pone en contacto con el cultivo de microalgas a través de una membrana semipermeable. La diferencia de presión osmótica entre el cultivo y la disolución de glicerol hace que el agua se transfiera al glicerol, lográndose así, sin adición de químicos ni gasto energético adicional la concentración del cultivo. Este procedimiento, permite que en los procesos posteriores al cultivo de microalgas se manejen menores volúmenes, con el subsecuente recorte en el gasto de equipos, suministros y energético. Alternativas: centrifugación, floculación, ósmosis con agua de mar.Universidad de Almerí

Production of pectinase by Bacillus subtilis EFRL 01 in a date syrup medium

A newly isolated Bacillus subtilis EFRL 01 was used to produce pectinases in batch fermentations on various inexpensive media. A mineral medium based on waste date syrup (15 g/L) as the carbon source and yeast extract (7.5 g/L) as the nitrogen source proved to be the most effective. A 48 h batch fermentation in this medium with a starting pH of 8.0 produced a pectinase titer of ~2,700 U/mL at the optimal fermentation temperature of 45°C. The optimal temperature, initial pH, the carbon source and its concentration, and the nitrogen source and its concentration, were identified after evaluation of multiple nutrient sources and fermentation conditions.Keywords: Polygalactouronase, Bacillus subtilis, fermentation, pectinases, date syru

Nitrile hydratase of Rhodococcus erythropolis: characterization of the enzyme and the use of whole cells for biotransformation of nitriles

The intracellular cobalt-type nitrile hydratase was purified from the bacterium Rhodococcuserythropolis. The pure enzyme consisted of two subunits of 29 and 30 kDa. The molecular weight of the native enzyme was estimated to be 65 kDa. At 25 °C the enzyme had a half-life of 25 h. The Michaelis–Menten constants K(m) and v(max) for the enzyme were 0.624 mM and 5.12 μmol/min/mg, respectively, using 3-cyanopyridine as the substrate. The enzyme-containing freely-suspended bacterial cells and the cells immobilized within alginate beads were evaluated for converting the various nitriles to amides. In a packed bed reactor, alginate beads (2 % alginate; 3 mm bead diameter) containing 200 mg/mL of cells, achieved a conversion of >90 % for benzonitrile and 4-cyanopyridine in 38 h (25 °C, pH 7.0) at a feed substrate concentration of 100 mM. The beads could be reused for up to six reaction cycles

Design of a Stacked-layer Tubular Photobioreactor for Microalgae Cultivation

A tubular photobioreactor is one of the most effective methods of microalgae cultivation because of the high solar receiver area and better biomass productivity. However, the pressure drop along the tubular solar receiver induces a relatively high dead zone. An optimal design is necessary to maximize biomass productivity. In this article, the proposed model can reduce the dead zone by up to 15% under a pressure drop of 106 Pa. To optimize the area requirement, three configurations with different stacking angles of 30, 45, and 60°, are simulated. The optimal 60° stacked-layer model is then connected to an airlift device to demonstrate the complete system. This model can circulate seawater inside the reactor at an average velocity of 0.188 m/s with 0.07 m/s of air inlet velocity. The radial flow can force the microalgae from the inner part of the tube to the outer part and back again throughout the entire stacked section. This turbulence will enhance biomass productivity because the microalgae are moved from the darker interior of the tube to the periphery where they are exposed to solar radiation. The optimal stacked-layer tubular photobioreactor has a slope of 60° with four stacked layers. This modification promotes the circulation of microalgae in both axial and radial directions

Recovery of red pigments from monascus purpureus FTC 5357 by extraction of fermented solids: Operational conditions and kinetics

Solvent extraction of red pigments from fermented solids is reported. The pigments were produced by solid-state fermentation of oil palm frond (OPF) biomass with the food-safe fungus Monascus purpureus FTC 5357. The effects of extraction solvent and other operational conditions (pH, temperature, agitation rate, contact time) on the recovery of pigments are discussed. The recovery was maximized using aqueous ethanol (60% ethanol by vol) as solvent at pH 6, 30 °C, with an extraction time of 16 h and an agitation rate of 180 rpm. A fermented solids dry mass of 1 g was used for each 160 mL of solvent during extraction. The kinetics of extraction were assessed by fitting the experimental data to different models. Peleg's model proved to be the best for describing solid-liquid extraction of the pigments under the above specified conditions. The highest extraction yield of red pigments under the above specified optimal conditions was 207±6.08 AU g 1 dry fermented solids

Production of lipids by tetraselmis sp. Grown in palm oil mill effluent

Malaysia is one of largest palm oil producer and exporter in the world, which generates million tons of palm oil mill effluent (POME) in a year. Discharge of POME into water bodies had created major environmental pollutions in Malaysia. Other side, POME also comprised of organic and inorganic pollutants that can become as potential medium source for cost-effective wastewater treatment and biofuel production. The fresh water microalgae Tetraselmis sp. was isolated from Taman Gelora, Kuantan, Pahang. The isolated pure strain of Tetrasemis sp. was cultivated in different concentration of palm oil mill effluent medium (5%, 10%, 15% and 20%, v/v). The results disclose that the maximal growth and biomass productivity was found in 10% (v/v) concentration of POME. The maximal dried biomass 0.832g/mL and extracted total lipid content 37% was obtained. The chemical characteristics of POME before and after cultivation were pH (7.9-8.1), BOD (38-11mg/L), COD (370-192mg/L), nitrate (247-10mg/L) and phosphate (22-0.7mg/L) respectively. Gas chromatography mass spectrometry depicts fatty acid methyl ester such as palmitic acid 55.03%, stearic acid 30.83 %, palmitoleic acid 7.67% oleic acid 4.84 %, linoleic acid 5.79% and followed by gamolenic acid 3.56 %. It proves that Tetraselmis sp. one potential candidate for biodiesel production by utilizing the palm oil mill effluent medium which can contribute to the reduction of the pollution