Continuous enantioselective esterification of trans-2-phenyl-1-cyclohexanol using a new Candida rugosa lipase in a packed bed bioreactor

Melamine-based Covalent Organic Polymers (MCOPs) as Lipase Nanocarrier for Recyclable Esters Hydrolysis and Transesterification

Present study has successfully synthesized melamine-based covalent organic polymers (MCOPs) and applied it as lipase carrier for recyclable esters hydrolysis and transesterification. The synthesized MCOPs are composed of dense nanosheet structures having a thickness of 3.5 nm. Three immobilization methods namely physical adsorption, cross-linking and carrier activation were employed to prepare the MCOPs-immobilized CRL. Cross-linked MCOPs-immobilized CRL (41.30 mg protein/g MCOPs) and carrier activated MCOPs-immobilized CRL (33.20 mg protein/g MCOPs) had higher enzyme loading as compared to physical absorb MCOPs-immobilized CRL (29.30 mg protein/g MCOPs). Nevertheless, physical absorb MCOPs-immobilized CRL demonstrated the highest esters hydrolysis (49.85 U) and transesterification (1.04 U) activities. Despite having the highest enzymatic activity, physical absorb MCOPs-immobilized CRL were not able to maintain its catalytic stability with more than 30% decreased in enzymatic activity during consecutive hydrolysis and transesterification activities. Meanwhile, cross-linked MCOPs-immobilized CRL demonstrated highest catalytic stability with highest enzymatic activities at the end of consecutive reactions. All the MCOPs-immobilized CRL can be easily recovered and reused through centrifugation with more than 85% of recovery rate.

Continuous flow biocatalysis

The continuous flow synthesis of active pharmaceutical ingredients, value-added chemicals, and materials has grown tremendously over the past ten years. This revolution in chemical manufacturing has resulted from innovations in both new methodology and technology. This field, however, has been predominantly focused on synthetic organic chemistry, and the use of biocatalysts in continuous flow systems is only now becoming popular. Although immobilized enzymes and whole cells in batch systems are common, their continuous flow counterparts have grown rapidly over the past two years. With continuous flow systems offering improved mixing, mass transfer, thermal control, pressurized processing, decreased variation, automation, process analytical technology, and in-line purification, the combination of biocatalysis and flow chemistry opens powerful new process windows. This Review explores continuous flow biocatalysts with emphasis on new technology, enzymes, whole cells, co-factor recycling, and immobilization methods for the synthesis of pharmaceuticals, value-added chemicals, and materials.

Silk-Cocoon Matrix Immobilized Lipase Catalyzed Transesterification of Sunflower Oil for Production of Biodiesel

Biodiesel from sunflower oil using lipase chemically immobilized on silk-cocoon matrix in a packed-bed bioreactor was investigated. The immobilization was demonstrated by field-emission scanning electron microscopy and activity study. The lipase loading was 738.74 U (~0.01 g lipase powder)/g-lipase-immobilized matrix. The Km (Michaelis-Menten constant) of the free and the immobilized lipase was 451.26 μM and 257.26 μM, respectively. Low Km value of the immobilized lipase is attributed to the hydrophobic nature of the matrix that facilitated the substrate diffusion to the enzyme surface. The biodiesel yield of 81.62% was obtained at 48 hours reaction time, 6 : 1 methanol : oil ratio (v/v), and 30°C. The immobilized lipase showed high operational stability at 30°C. The substrate conversion was only marginally decreased till third cycle (each of 48 hours duration) of the reaction since less than even 5% of the original activity was decreased in each of the second and third cycle. The findings demonstrated the potential of the silk-cocoon as lipase immobilization matrix for industrial production of biodiesel.

Lipase-immobilized biocatalytic membranes for biodiesel production

Microbial lipase from Candida rugosa (Amano AY-30) has good transesterification activity and can be used for biodiesel production. In this study, polyvinylidene fluoride (PVDF) membrane was grafted with 1,4-diaminobutane and activated by glutaraldehyde for C. rugosa lipase immobilization. After immobilization, the biocatalytic membrane was used for producing biodiesel from soybean oil and methanol via transesterification. Response Surface Methodology (RSM) in combination with a 5-level-5-factor central composite rotatable design (CCRD) was employed to evaluate the effects of reaction time, reaction temperature, enzyme amount, substrate molar ratio and water content on the yield of soybean oil methyl ester. By ridge max analysis, the predicted and experimental yields under the optimum synthesis conditions were 97% and 95%, respectively. The lipase-immobilized PVDF membrane showed good reuse ability for biodiesel production, enabling operation for at least 165 h during five reuses of the batch, without significant loss of activity.

Reactivity of Pure Candida rugosa Lipase Isoenzymes (Lip1, Lip2, and Lip3) in Aqueous and Organic Media. Influence of the Isoenzymatic Profile on the Lipase Performance in Organic Media

Three pure isoenzymes from Candida rugosa lipase (CRL: Lip1, Lip2, and Lip3) were compared in terms of their stability and reactivity in both aqueous and organic media. The combined effect of temperature and pH on their stability was studied applying a factorial design. The analysis of the response surfaces indicated that Lip1 and Lip3 have a similar stability, lower than that of Lip2. In aqueous media, Lip3 was the most active enzyme on the hydrolysis of p-nitrophenyl esters, whereas Lip1 showed the highest activity on the hydrolysis of most assayed triacylglycerides. The highest differences among isoenzymes were found in the hydrolysis of triacylglycerides. Thus, a short, medium, and long acyl chain triacylglyceride was the preferred substrate for Lip3, Lip1, and Lip2, respectively. In organic medium, Lip3 and Lip1 provided excellent results in terms of enantioselectivity in the resolution of ibuprofen (EF value over 0.90) and conversion, whereas initial esterification rate was higher for Lip3. However, the use of Lip2 resulted in lower values of conversion, enantiomeric excess, and enantioselectivity. In the case of trans-2-phenyl-1-cyclohexanol (TPCH) resolution, initial esterification rates were high except for Lip3, which also produced poor results in conversion and enantiomeric excess. The performance of the pure isoenzymes in the enantioselectivity esterification of these substrates was compared with different CRL crude preparations with known isoenzymatic content and the different results could not be explained by their isoenzymatic profile. Therefore, it can be concluded that other factors can also affect the catalysis of CRL and only the reproducibility between powders can ensure the reproducibility in synthesis reactions.

Studies of optimum conditions for covalent immobilization of Candida rugosa lipase on poly(gamma-glutamic acid) by RSM

Poly(gamma-glutamic acid) (gamma-PGA) is a material of polymer. Immobilization of Candida rugosa lipase (Lipase AY-30) by covalent binding on gamma-PGA led to a markedly improved performance of the enzyme. Response surface methodology (RSM) and 3-level-3-factor fractional factorial design were employed to evaluate the effects of immobilization parameters, such as immobilization time (2-6h), immobilization temperature (0-26 degrees C), and enzyme/support ratio (0.1-0.5, w/w). Based on the analysis of ridge max, the optimum immobilization conditions were as follows: immobilization time 2.3h, immobilization temperature 13.3 degrees C, and enzyme/support ratio 0.41 (w/w); the highest lipase activity obtained was 1196 U/mg-protein.