Nb-MCM-Type Mesoporous Material Synthesis Using Ionic Solid as Structure-Directing Agent for In Situ Lipase Immobilization

Application of Stemphylium lycopersici Extracts Immobilized on MCM-48type Mesoporous Materials as Biocatalysts for Monoacylglycerol Production

Monoacylglycerols are eco-friendly and inexpensive emulsifiers with a range of applications. The traditional synthetic route is not eco-friendly, while enzymatic catalysis offers milder reaction conditions and higher selectivity. However, its application still is limited due to the costs. In this context, endophytic fungi can be source to new biocatalysts with enhanced catalytic activity. Based on this perspective, the aim of this study was perform the synthesis of MAG's through transesterification reactions of solketal and different vinyl esters, using crude and immobilized lipolytic extracts from the endophytic fungi Stemphylium lycopersici, isolated from Humiria balsamifera. The reactions were conducted using 100 mg of biocatalyst, 1 mmol of substrates, 9 : 1 n-heptane/acetone, at 40 °C, 200 rpm for 96 h. In the reactions using the ILE and stearate, laureate and decanoate vinyl esters it was possible to obtain the correspondent products with conversion rates of 52-75 %. Also, according to the structure drivers used in MCM-48 synthesis, different morphologies and conversions rates were observed. Employing [C16MI] Cl, [C14MI] Cl and [C4MI] Cl, the 1-lauroyl- glycerol conversion was 36 %, 79 % and 44 %, respectively. This is the first work involving the immobilization of an endophytic fungi and its utilization as a biocatalyst in the production of MAG's.

Immobilization of Lipase from Candida antarctica B (CALB) by Sol-Gel Technique Using Rice Husk Ash as Silic Source and Ionic Liquid as Additive

This work presents the immobilization in situ of commercial lipase from Candida antarctica B (CALB) by the sol-gel technique (xerogel) using silica from rice husk ash (RHA) as a source of silicon. It was used the Ionic Liquid (IL) 1-octyl-3-methylimidazolium bromide (C8MI.Br) as additive. The immobilized derivatives were characterized per SEM, XRD, and per method BET. The enzymatic activity of xerogels was evaluated with different tests, these being the reactional thermal analysis, immobilization yield, and operational and storage stability. The XDR showed that the obtained xerogels have halos in the region between 15 and 35° (2θ) what characterizes it as amorphous materials. The SEM analysis of xerogel shows irregular particles with dimensions less than 20 μm. The immobilized presented an esterification activity (EA) with 263.2 and 213.8 U/g, with and without IL, respectively, higher than the free enzyme (169.6 U/g). The immobilized, with and without IL, presented a significant improvement in the activity performance in relation to free enzyme for the three reactional temperatures (40, 60, and 80 °C) evaluated. The operational stability demonstrated that is possible to use xerogel without ionic liquid for 17 recycles and 21 recycles in IL presence. This methodology allows the preparation of new highly active and selective enzyme catalysts using the rice husk ash as a source of silicon, and the ionic liquid [C8MI]Br as additive. Furthermore, the new materials can provide greater viability in the processes, ensuring longer catalyst life.

In Situ Calb Enzyme Immobilization in Mesoporous Material Type MCM-48 Synthesis Using Ionic Solid [C14MI]Cl as Structure-Directing Agent

MCM-48 mesoporous support was synthesized with the ionic solid 1-tetradecyl-3-methylimidazolium chloride ([C14MI]Cl) as a structure-directing agent for in situ immobilization of Candida antarctica B (CALB). The MCM-48[C14MI]Cl support showed characteristics of mesoporous material of interest, with a pore size of 20.30 and 73.41 A for the support without and with the enzyme, respectively. The elongation of the carbonic chain of the ionic solid directly influenced the increase in the specific area and pore volume of the material. In addition, the decrease in the specific area and pore volume for support with the enzyme showed the effectiveness of immobilization in situ. It was possible to obtain the ideal levels for the best activities of esterification of the enzyme with optimization of a mathematical model. The optimized variables were 0.31 g of enzyme and 3.35% of ionic solid with a maximum esterification activity of 392.92 U/g and 688% of yield. The support showed residual activity above 50% when stored under refrigeration for 75 days. At 60 and 80 °C, the enzyme immobilized on the support retained more than 80 and 40% of its residual activity, respectively. In addition, the support presented the possibility of reuse for up to 10 cycles with residual activity of approximately 50%. The support synthesized in the present study presents a great industrial opportunity for the immobilization and use of the CALB enzyme.

Evaluation of Different Ionic Liquids as Additives in the Immobilization of Lipase CAL B by Sol-Gel Technique

Sol-gel technique aiming enzymatic immobilization in situ with ionic liquids as additives is poorly studied. In this process, the addition of the enzyme is carried out in the synthesis of the support. The characteristics of ionic liquids, such as low vapor pressure, thermal stability, and non-flammability, make them strong candidates for use as immobilization additives. The objective of the present study was to immobilize the Candida antarctica B lipase by the sol-gel technique using ionic liquids as additives. The optimum points determined for ionic liquids 1-butyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, and 1 hexadecyl-3-methylimimidazolium were 0.30, 0.27, and 0.22 g/mL of enzyme and 1.60, 1.52, and 1.52% of additive, respectively. The amount of enzyme and ionic liquids used in aerogel immobilization was the same as the optimized values in the xerogel immobilization process (for each ionic liquid). Ionic liquids proved to be good additives in the enzymatic immobilization process. Xerogel, regardless of the ionic liquid, presented a greater number of use cycles and better thermal stability compared to aerogel.