Catalytic potential of a nitrocellulose membrane-immobilized lipase in aqueous and organic media

Characterization of a novel lipase from Bacillus licheniformis NCU CS-5 for applications in detergent industry and biodegradation of 2,4-D butyl ester

Enzymatic degradation has become the most promising approach to degrading organic ester compounds. In this study, Bacillus licheniformis NCU CS-5 was isolated from the spoilage of Cinnamomum camphora seed kernel, and its extracellular lipase was purified, with a specific activity of 192.98 U/mg. The lipase was found to be a trimeric protein as it showed a single band of 27 kDa in SDS-PAGE and 81 kDa in Native-PAGE. It was active in a wide range of temperatures (5-55 °C) and pH values (6.0-9.0), and the optimal temperature and pH value were 40 °C and 8.0, respectively. The enzyme was active in the presence of various organic solvents, metal ions, inhibitors and surfactants. Both crude and purified lipase retained more than 80% activity after 5 h in the presence of commercial detergents, suggesting its great application potential in detergent industry. The highest activity was found to be towards medium- and long-chain fatty acids (C₆-C₁₈). Peptide mass spectrometric analysis of the purified lipase showed similarity to the lipase family of B. licheniformis. Furthermore, it degraded more than 90% 2,4-D butyl ester to its hydrolysate 2,4-D within 24 h, indicating that the novel lipase may be applied to degrade organic ester pesticides.

Novel approach using activated cellulose film for efficient immobilization of purified diamine oxidase to enhance enzyme performance and stability

The presence of various contaminants in foodstuffs has led to serious public health concerns. Diamine oxidase (DAO) has attracted tremendous attention for guarding food safety as well as clinical and environmental industries. In this study, DAO from Pisum sativum (Pea) seedlings was extracted and purified by dialysis and gel filtration. Purified DAO was covalently immobilized onto the surface of nitrocellulose membrane using glutaraldehyde. The obtained bioaffinity support has efficiently shown high yield immobilization of DAO from pea seedlings. The optimal conditions of free and immobilized DAO activity were evaluated against the substrate, Putrescine dihydrochloride. The influence of pH, temperature, storage stability, and reusability of immobilized enzyme with comparison to the free enzyme was studied and the results showed that the stabilities were significantly enhanced compared with free counterpart. Residual activity of the immobilized enzyme was 59% of the initial activity after being recycled 10 times. We approve that this novel low cost immobilized DAO carrier presents a new approach in large scale applications.

Ascorbyl palmitate synthesis in an organic solvent system using a Celite-immobilized commercial lipase (Lipolase 100L)

Ascorbyl palmitate was synthesized using a Celite-immobilized commercial lipase (Lipolase 100L) in dimethylsulfoxide (DMSO) as an organic solvent system. Lipase immobilized by surface adsorption onto Celite 545 matrix and subsequently exposed to 1 % glutaraldehyde showed 75 % binding of protein. The Celite-bound lipase was optimally active at 75 °C and pH 8.5 under shaking and showed maximum hydrolytic activity toward p-NPP as a substrate. The bound lipase was found to be stimulated only in the presence of Al³⁺ and EDTA. All surfactants (Tween-20, Tween-80 and Triton X-100) had an inhibitory effect on lipase activity. The optimization of various reaction conditions of ascorbyl palmitate was achieved considering one factor at a time. The esterification of ascorbic acid and palmitic acid was carried out with 1 M ascorbic acid and 2.5 M palmitic acid in DMSO at 75 °C for 18 h under shaking (120 rpm). Molecular sieves had an important effect on the ester synthesis resulting in an enhanced yield. The by-product (H₂O) produced in the reaction was scavenged by the molecular sieves (20 mg/ml) added in the reaction mixture which enhanced the ester yield to 80 %. The characterization of synthesized ester was done through FTIR spectroscopy.

Lipase catalysis in organic solvents: advantages and applications

Lipases are industrial biocatalysts, which are involved in several novel reactions, occurring in aqueous medium as well as non-aqueous medium. Furthermore, they are well-known for their remarkable ability to carry out a wide variety of chemo-, regio- and enantio-selective transformations. Lipases have been gained attention worldwide by organic chemists due to their general ease of handling, broad substrate tolerance, high stability towards temperatures and solvents and convenient commercial availability. Most of the synthetic reactions on industrial scale are carried out in organic solvents because of the easy solubility of non-polar compounds. The effect of organic system on their stability and activity may determine the biocatalysis pace. Because of worldwide use of lipases, there is a need to understand the mechanisms behind the lipase-catalyzed reactions in organic solvents. The unique interfacial activation of lipases has always fascinated enzymologists and recently, biophysicists and crystallographers have made progress in understanding the structure-function relationships of these enzymes. The present review describes the advantages of lipase-catalyzed reactions in organic solvents and various effects of organic solvents on their activity.

Immobilized Hydrolytic Enzymes Exhibit Antibiofilm Activity Against Escherichia coli at Sub-Lethal Concentrations

The effects of two commercially available immobilized enzymes (namely the glycosidase pectinase and the protease subtilisin A) at sub-lethal concentrations were investigated in terms of their influence on biofilm genesis, on the composition of the biofilm matrix, and their antibiotic synergy against Escherichia coli biofilm, used as a model system of bacterial biofilms. The best antibiofilm performance of solid-supported hydrolases was obtained at the surface concentration of 0.022 and 0.095 U/cm(2) with a reduction of 1.2 and 2.3 log CFU/biofilm for pectinase and subtilisin, respectively. At these enzyme surface concentrations, the biocatalysts affected the structural composition of the biofilm matrix, impacting biofilm thickness. Finally, the immobilized hydrolases enhanced biofilm sensitivity to a clinically relevant concentration of the antibiotic ampicillin. At the final antibiotic concentration of 0.1 mg/ml, a reduction of 2 and 3.5 log10 units in presence of 0.022 Upectinase/cm(2) and 0.095 Usubtilisin/cm(2) was obtained, respectively, in comparison the antibiotic alone. Immobilized pectinase and subtilisin at sub-lethal concentrations demonstrated a great potential for antibiofilm applications.

Organic solvent tolerant lipases and applications

Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s) could be performed in water-restricted organic media as organic solvent(s) not only improve(s) the solubility of substrate and reactant in reaction mixture but also permit(s) the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.