Performance of a continuous Taylor–Couette–Poiseuille vortex flow enzymic reactor with suspended particles

Isolation of Fatty Acids from the Enzymatic Hydrolysis of Capsaicinoids and Their Use in Enzymatic Acidolysis of Coconut Oil

Herein we report the optimization of enzymatic hydrolysis of a mixture of capsaicinoids, capsaicin and dihydrocapsaicin obtained from chili peppers, and the utilization of the isolated fatty acids for the modification of coconut oil using enzyme catalyzed acidolysis. This work was carried out as the fatty acids that can be isolated from capsaicinoid hydrolysis have been shown to possess interesting biological properties. These biological properties could be better exploited by incorporating the fatty acids into a suitable delivery vehicle. The enzymatic hydrolysis of the mixture of capsaicin and dihydrocapsaicin was carried out using Novozym® 435 in phosphate buffer (pH 7.0) at 50℃. The enzyme catalyst could be reused in multiple cycles of the hydrolysis reaction. The desired 8-methyl-6-trans-nonenoic acid and 8-methylnonanoic acid were isolated from the hydrolysis reaction mixture using a simple extraction procedure with a 47.8% yield. This was carried out by first extracting the reaction mixture at pH 10 with ethyl acetate to remove any dissolved capsaicinoids and vanillyl amine side product. The fatty acids were isolated after adjustment of the pH of the reaction mixture to 5 and second extraction with ethyl acetate. The acidolysis of coconut oil with the obtained fatty acids was performed using Lipozyme® TL IM. The performance of the acidolysis reaction was evaluated using 1H-NMR spectroscopy and verified in selected cases using gas chromatography. The best performing conditions involved carrying out the acidolysis reaction at 60℃ with a 1.2 w/w ratio of the fatty acids to coconut oil and 10% enzyme loading for 72 h. This resulted in the incorporation of 26.61% and 9.86% of 8-methyl-6-trans-nonenoic acid and 8-methylnonanoic acid, respectively, into the modified coconut oil product. This product can act as a potential delivery vehicle for these interesting compounds.

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

Enzyme immobilization has been developing since the 1960s and although many industrial biocatalytic processes use the technology to improve enzyme performance, still today we are far from full exploitation of the field. One clear reason is that many evaluate immobilization based on only a few experiments that are not always well-designed. In contrast to many other reviews on the subject, here we highlight the pitfalls of using incorrectly designed immobilization protocols and explain why in many cases sub-optimal results are obtained. We also describe solutions to overcome these challenges and come to the conclusion that recent developments in material science, bioprocess engineering and protein science continue to open new opportunities for the future. In this way, enzyme immobilization, far from being a mature discipline, remains as a subject of high interest and where intense research is still necessary to take full advantage of the possibilities.

Vortex flow reactor assessment for the purification of monoclonal antibodies from unclarified broths

The vortex flow reactor (VFR) can be used in many chemical engineering applications. This paper assesses its novel use in the purification of monoclonal antibodies from cell broth. To this end, the IgG2a antibody was purified from the unclarified fermentation broth of transgenic mouse 55/6 hybridoma cells. Visual experiments showed that the VFR worked in the laminar vortices flow regime and the vortices displaced slightly faster than the axial flow. The VFR has the advantage of creating two sorts of flows: axial flow to produce the expanded bed and an extra vortex flow to avoid channeling and stabilize the expanded bed, the hydrodynamic behavior of which is plug flow with an experimental Pèclet number higher than 20. The pH was adjusted in the untreated fermentation broth, which was directly introduced into the reactor thus reducing the number of stages. The IgG2a purification was carried out in a single device via two steps: antibody adsorption in the expanded bed and antibody elution in the settled bed using Streamline rProtein A. A thirty-fold increase in the high-purity antibody concentration was achieved at the top of the pH5 elution peak with a total recovery of 93.1% (w/w) between elution peaks pH 5 and 3.

Improving the Yields and Reaction Rate in the Ethanolysis of Soybean Oil by Using Mixtures of Lipase CLEAs

Due to the heterogeneity of oils, the use of mixtures of lipases with different activity for a large number of glycerol-linked carboxylic acids that compose the substrate has been proposed as a better alternative than the use of one specific lipase preparation in the enzymatic synthesis of biodiesel. In this work, mixtures of lipases from different sources were evaluated in their soluble form in the ethanolysis of soybean oil. A mixture of lipases (50% of each lipase, in activity basis) from porcine pancreas (PPL) and Thermomyces lanuginosus lipase (TLL) gave the highest fatty acid ethyl ester (FAEE) yield (around 20 wt.%), while the individual lipases gave FAEE yields 100 and 5 times lower, respectively. These lipases were immobilized individually by the cross-linked enzyme aggregates (CLEAs) technique, yielding biocatalysts with 89 and 119% of expressed activity, respectively. A mixture of these CLEAs (also 50% of each lipase, in activity basis) gave 90.4 wt.% FAEE yield, while using separately CLEAs of PPL and TLL, the FAEE yields were 84.7 and 75.6 wt.%, respectively, under the same reaction conditions. The mixture of CLEAs could be reused (five cycles of 6 h) in the ethanolysis of soybean oil in a vortex flow-type reactor yielding an FAEE yield higher than 80% of that of the first batch.

Preparation of Crosslinked Enzyme Aggregates of a Thermostable Cyclodextrin Glucosyltransferase from Thermoanaerobacter sp. Critical Effect of the Crosslinking Agent

Crosslinked enzyme aggregates (CLEAs) of a thermostable cyclodextrin glucosyltransferase (CGTase) from Thermoanaerobacter sp. have been prepared for the production of cyclodextrins (CDs). Different parameters in the precipitation (nature and concentration of precipitant) and crosslinking steps (time of reaction with cross-linker, nature and concentration of the crosslinker) were evaluated on the production of CLEAs of CGTase. Among the seven studied precipitants, acetone with a 75% (v/v) concentration produced the aggregates of CGTase with higher activity, which retained 97% of the initial activity. Concerning the cross-linker (glutaraldehyde, starch–aldehyde, and pectin–aldehyde), starch–aldehyde produced the most active CLEAs. The use of bovine serum albumin as co-feeder decreased the expressed activity. Addition of polyethylenimine at the end of cross-linking step prevented the leakage of the enzyme and the subsequent Schiff’s bases reduction with sodium borohydride permitted to maintain 24% of the initial activity even with the large dextrin as substrate. The optimal conditions for the immobilization process required were defined as 75% (v/v) acetone as precipitation reagent for 1 h at 20 °C, 20 mM starch–aldehyde as crosslinking reagent for 2 h at 20 °C, treatment with 1 mg/mL of polyethylenimine for 5 min, reduction with 1 mg/mL of sodium borohydride. The CLEAs of CGTase were active catalyst (similarly to the free enzyme) in the production of cyclodextrins at 50 °C and pH 6.0 for 6 h reaction, maintaining intact their structures. Besides this, after five cycles of 3 h the total cyclodextrin yield was 80% of the initial value (first batch, with around 45% CD yield).

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

Actinometric and biodosimetric evaluation of UV-C dose delivery in annular, Taylor–Coutte and coiled tube continuous systems

In this study, the evaluation of the performance of two thin-film UV-C reactors (annular and Taylor–Couette) and a coiled tube system is presented using actinometry and biodosimetry methods. The iodide/iodate actinometry method was found suitable for comparison of the efficiency of UV-C dose delivery of the UV-C continuous flow systems. Inactivation kinetics of Escherichia coli ATCC 8739 in quarter-strength Ringer’s solution (absorption coefficient α254 nm ∼ 0 cm−1) at various flow conditions at Reynolds numbers in the range of 26 to 3000 showed a good correlation between the different reactor types. In high UV-C absorbing liquids, the inactivation efficiency increases due to the improved radial mixing. The inactivation performance of the Taylor–Couette system correlates to the annular reactor when no rotation force is applied. The residence time distributions showed the narrowest distribution with the coiled tube system at comparable flow rates. The results indicate that, despite the laminar flow conditions, the performance of the Taylor–Couette unit becomes equal to the turbulent flow conditions of the coiled tube reactor by rotation of the inner cylinder.

Immobilization of glucoamylase by adsorption on carbon supports and its application for heterogeneous hydrolysis of dextrin

Glucoamylase (GA) was immobilized by adsorption on carbon support: on Sibunit, on bulk catalytic filamentous carbon (bulk CFC) and on activated carbon (AC). This was used to prepare heterogeneous biocatalysts for the hydrolysis of starch dextrin. The effect of the texture characteristics and chemical properties of the support surface on the enhancement of the thermal stability of the immobilized enzyme was studied, and the rates of the biocatalyst's thermal inactivation at 65-80 degrees C were determined. The thermal stability of glucoamylase immobilized on different carbon supports was found to increase by 2-3 orders of magnitude in comparison with the soluble enzyme, and decrease in the following order: GA on Sibunit>GA on bulk CFC>GA on AC. The presence of the substrate (dextrin) was found to have a significant stabilizing effect. The thermal stability of the immobilized enzyme was found to increase linearly when the concentration of dextrin was increased from 10 wt/vol % to 50 wt/vol %. The total stabilization effect for glucoamylase immobilized on Sibunit in concentrated dextrin solutions was about 10(5) in comparison with the enzyme in a buffer solution. The developed biocatalyst, 'Glucoamylase on Sibunit' was found to have high operational stability during the continuous hydrolysis of 30-35 wt/vol % dextrin at 60 degrees C, its inactivation half-time (t1/2) exceeding 350 h. To improve the starch saccharification productivity, an immersed vortex reactor (IVR) was designed and tested in the heterogeneous process with the biocatalyst 'Glucoamylase on Sibunit'. The dextrin hydrolysis rate, as well as the process productivity in the vortex reactor, was found to increase by a factor of 1.2-1.5 in comparison with the packed-bed reactor.