Effect of cyclic and acyclic surfactants on the activity of Candida rugosa lipase

Bioconversion of waste glycerol into viscosinamide by Pseudomonas fluorescens DR54 and its activity evaluation

Lipopeptides, derived from microorganisms, are promising surface-active compounds known as biosurfactants. However, the high production costs of biosurfactants, associated with expensive culture media and purification processes, limit widespread industrial application. To enhance the sustainability of biosurfactant production, researchers have explored cost-effective substrates. In this study, crude glycerol was evaluated as a promising and economical carbon source in viscosinamide production by Pseudomonas fluorescens DR54. Optimization studies using the Box - Behnken design and response surface methodology were performed. Optimal conditions for viscosinamide production including glycerol 70.8 g/L, leucine 2.7 g/L, phosphate 3.7 g/L, and urea 9.3 g/L were identified. Yield of viscosinamide production, performed under optimal conditions, reached 7.18 ± 0.17 g/L. Preliminary characterization of viscosinamide involved the measurement of surface tension. The critical micelle concentration of lipopeptide was determined to be 5 mg/L. Furthermore, the interactions between the viscosinamide and lipase from Candida rugosa (CRL) were investigated by evaluating the impact of viscosinamide on lipase activity and measuring circular dichroism. It was observed that the α-helicity of CRL increases with increasing viscosinamide concentration, while the random coil structure decreases.

Biotransformation of Raw Mango Seed Waste into Bacterial Hydrolytic Enzymes Enhancement Via Solid State Fermentation Strategy

Solid waste generation is a huge contributor to environmental pollution issues, and food wastes are prominent in this category due to their large generation on a day-to-day basis. Thus, the settlement of daily food waste is one of the major constraints and needs innovative manufacturing sheme to valorize solid waste in sustainable manner. Moreover, these food wastes are rich in organic content, which has promising scope for their value-added products. In the present study, raw mango seed waste has been biotransformed to produce bacterial hydrolytic enzymes as feedstock. On investigating the impact of substrate, the highest bacterial cellulase production was recorded to be 18 IU/gds FP (filter paper) in 24 h of microbial incubation at 5 g of substrate in solid-state fermentation (SSF). Furthermore, at 40 °C and pH 6.0, 23 IU/gds FP enzyme could be produced in 24 h of SSF. Beside this, on comparing the influence of inorganic and organic nitrogen sources, urea has been found to provide better cellulase production, which yielded 28 IU/gds FP in 24 h of incubation, along with 77 IU/gds BG (β-glucosidase) and 89 IU/gds EG (endoglucanase). On the other hand, Tween-40 and Tween-80, two different surfactants, were employed at a 1.0% concentration for 24 h of incubation. It was noticed that Tween-80 showed complete enzyme activity at 24 h, which was found to be relatively superior to that of Tween-40. This study may have potential utility in enzyme production using mango seed as a food waste for various industrial applications.

Surfactant-based metal-organic frameworks (MOFs) in the preparation of an active biocatalysis

Metal-organic frameworks (MOFs) are used as ideal support materials thanks to their unique properties and have become the focus of interest in enzyme immobilization studies, especially in recent years. In order to increase the catalytic activity and stability of Candida rugosa lipase (CRL), a new fluorescence-based MOF (UiO-66-Nap) derived from UiO-66 was synthesized. The structures of the materials were confirmed by spectroscopic techniques such as FTIR, ¹H NMR, SEM, and PXRD. CRL was immobilized on UiO-66-NH₂ and UiO-66-Nap by adsorption technique and immobilization and stability parameters of UiO-66-Nap@CRL were examined. Immobilized lipases UiO-66-Nap@CRL exhibited higher catalytic activity (204 U/g) than UiO-66-NH₂@CRL (168 U/g), which indicates that the immobilized lipase (UiO-66-Nap@CRL) carries sulfonate groups, this is due to strong ionic interactions between the surfactant's polar groups and certain charged locations on the protein surface. The Free CRL lost its catalytic activity completely at 60 °C after 100min, while UiO-66-NH₂@CRL and UiO-66-Nap@CRL retained 45% and 56% of their catalytic activity at the end of 120min, respectively. After 5 cycles, the activity of UiO-66-Nap@CRL remained 50%, while the activity of UiO-66-NH₂@CRL was about 40%. This difference is due to the surfactant groups (Nap) in UiO-66-Nap@CRL. These results show that the newly synthesized fluorescence-based MOF derivative (UiO-66-Nap) can be an ideal support material for enzyme immobilization and can be used successfully to protect and increase the activities of enzymes.

Immobilization of Interfacial Activated Candida rugosa Lipase Onto Magnetic Chitosan Using Dialdehyde Cellulose as Cross-Linking Agent

Candidarugosa lipase (CRL) was activated with surfactants (sodium dodecyl sulfate [SDS]) and covalently immobilized onto a nanocomposite (Fe₃O₄-CS-DAC) fabricated by combining magnetic nanoparticles Fe₃O₄ with chitosan (CS) using polysaccharide macromolecule dialdehyde cellulose (DAC) as the cross-linking agent. Fourier transform infrared spectroscopy, transmission electron microscope, thermogravimetric analysis, and X-ray diffraction characterizations confirmed that the organic–inorganic nanocomposite support modified by DAC was successfully prepared. Enzymology experiments confirmed that high enzyme loading (60.9 mg/g) and 1.7 times specific enzyme activity could be obtained under the optimal immobilization conditions. The stability and reusability of immobilized CRL (Fe₃O₄-CS-DAC-SDS-CRL) were significantly improved simultaneously. Circular dichroism analysis revealed that the active conformation of immobilized CRL was maintained well. Results demonstrated that the inorganic–organic nanocomposite modified by carbohydrate polymer derivatives could be used as an ideal support for enzyme immobilization.

Calix[4]arene tetracarboxylic acid-treated lipase immobilized onto metal-organic framework: Biocatalyst for ester hydrolysis and kinetic resolution

Metal organic frameworks (MOFs) are hybrid organic inorganic materials with unique properties such as well-defined pore structure, extremely high surface area, excellent chemical-thermal stability. MOFs-based constructs have been extensively engineered and used for applications, such as enzyme immobilization for bio-catalysis. To obtained a zeolitic imidazole framework-8 (ZIF-8) for enzyme immobilization, Candida rugosa lipase (CRL) was pretreated with calix [4]arene tetracarboxylic acid (Calix) and reacted with Zn and imidazole by co-precipitation method. The prepared biocomposite was characterized by SEM, EDX, FT-IR, and XRD. The prepared CRL@Calix-ZIF-8 with high encapsulation efficiency showed improved resistance to alkali and thermal conditions. The CRL@Calix-ZIF-8 with the biocatalytic activity was 2-folds higher than that of the CRL@ZIF-8 (without Calix). The free lipase lost its catalytic activity completely at 60 °C after 100 min, while the CRL@Calix-ZIF-8 and CRL@ZIF-8 retained about 84% and 73%. It was found that CRL@Calix-ZIF-8 and CRL@ZIF-8 still retained ~83 and 67% of catalytic activity after its 6th use, respectively. The kinetic resolution of the immobilized lipases was examined for enantioselective hydrolysis of racemic naproxen methyl ester. CRL@Calix-ZIF-8 showed enantioselectivity against the racemic naproxen methyl ester, with E = 183 and 131 compared to the CRL@ZIF-8.