Lipolytic activity of lipases from different strains of Yarrowia lipolytica in hydrolysed vegetable fats at low temperature and water activity

Yarrowia lipolytica is a very important yeast because many strains from this yeast are able to produce the extracelular lipases. Cold active lipase is one of the important and widely used enzymes whose spectrum of applications has widened in many industries such as in detergent formulations. food industry, leather processing, environmental bioremediations. and fine chemical synthesis as well as in pharmaceutical industries. Cold active lipases are largely distributed in microorganisms surviving at low temperatures. near 4 degrees C. Although a number of lipase producing sources are available. only a few bacteria and yeasts were exploited for the production of active lipases. Attempts have been made from time to time to isolate cold active lipases from these microorganisms having high activity at low temperatures. These lipases show great interests in different applications of food and chemistry industry. In this study, it was evaluated the lipolytic activity of lipases from different strains of Yarrowia lipolytica in the critical conditions. The aim of this research was to evaluate the ability of different Yarrowia lipolytica strains, having different origin. to grow and to produce the lipases at low temperature (4 degrees C). 13 Lipases from Yarrowia lipolytica coded as PO1, PO11. RO3, RO15, Y10, Y22. LP PAST to la, LC TL TO 4b, LP TQ to 1a, LN2, 1 II YL 4, 16B and 27D. were used for enzymatic hydrolysis of two crude exotic fats, like: white palm kernel fat and shea fat. The conditions of hydrolysis was a low temperature (4 degrees C) and low values water activity (aw 0.98 and 0.96). The lipolytic activity of lipases was evaluated by measuring the diameters of hydrolysis zone. At 4 degrees C and aw 0.98, the Yarrowia lipolytica strains such as : RO3, 1 II YL4 and LC TL to 4b produced the cold active lipases that had the higher lipolytic activity on the palm kernel fat. In the same conditions, lipases from yeast strains like: RO3, RO15 and 1 II YL4 demonstrated a strong lipolytic activity on the shea fat At aw 0.96, the lipase produced by the same strains of Yarrowia lipolytica shows a higher specificity of palm kernel fat and shea f

Effect of Gas Composition on Surfactant Injectivity in a Surfactant-Alternating-Gas Foam Process

Aqueous foam is a dispersion of gas in liquid, where the liquid acts as the continuous phase and the gas is separated by thin liquid films stabilized by a surfactant. Foam injection is a widely used technique in various applications, including CO2 sequestration, enhanced oil recovery, soil remediation, etc. Surfactant-alternating-gas (SAG) is a preferred approach for foam injection, and injectivity plays a vital role in determining the efficiency of the SAG process. Different gases can be applied depending on the process requirements and availability. However, the underlying mechanisms by which gas composition impacts injectivity are not yet fully understood. In this work, the effect of gas composition on fluid behavior and injectivity in a SAG process was investigated using three gases: N2, CO2, and Kr. Our observations revealed that gas solubility in liquid was key for the formation and evolution of liquid fingers, and therefore was very important for liquid injectivity. A lower gas solubility in liquid led to a slower increase in surfactant solution injectivity. In addition, the development of surfactant solution injectivity took significantly longer when the surfactant solution was partially pre-saturated compared to when it was unsaturated. Additionally, the propagation of the collapsed-foam bank during gas injection was accelerated when the gas had a greater solubility in water.Reservoir EngineeringAtmospheric Remote Sensin

Liquid injectivity in a SAG foam process: Effect of permeability

Foam is utilized in enhanced oil recovery and CO2 sequestration. Surfactant-alternating-gas (SAG) is a preferred approach for placing foam into reservoirs, due to it enhances gas injection and minimizes corrosion in facilities. Our previous studies with similar permeability cores show that during SAG injection, several banks occupy the area near the well where fluid exhibits distinct behaviour. However, underground reservoirs are heterogeneous, often layered. It is crucial to understand the effect of permeability on fluid behaviour and injectivity in a SAG process. In this work, coreflood experiments are conducted in cores with permeabilities ranging from 16 to 2300 mD. We observe the same sequence of banks in cores with different permeabilities. However, the speed at which banks propagate and their overall mobility can vary depending on permeability. At higher permeabilities, the gas-dissolution bank and the forced-imbibition bank progress more rapidly during liquid injection. The total mobilities of both banks decrease with permeability. By utilizing a bank-propagation model, we scale up our experimental findings and compare them to results obtained using the Peaceman equation. Our findings reveal that the liquid injectivity in a SAG foam process is misestimated by conventional simulators based on the Peaceman equation. The lower the formation permeability, the greater the error.Reservoir Engineerin