Synthesis of ethyl acetate employing celite-immobilized lipase of Bacillus cereus MTCC 8372

Synthesis of Feruloyl Ester Using Bacillus subtilis AKL 13 Lipase Immobilized on Celite® 545

The lipophilic antioxidants, glyceryl ferulate and feruloyl glyceryl linoleate, were synthesized using lipase from Bacillus subtilis AKL 13. The extracellular lipase was produced by cultivation of the strain in modified minimal medium and the enzyme was recovered by fractionation at 80% ammonium salt saturation. The concentrated enzyme with the specific activity of (4647±66) U/mg was immobilized on Celite® 545 and crosslinked using glutaraldehyde. The prepared enzyme catalyst was used for esterification of ferulic and linoleic acids with glycerol separately in hexane butane solvent system at 50 °C and 3.144×g agitation. The maximum ester conversion of 94% of feruloyl glyceryl linoleate was achieved at 48 h, whereas only 35% of glyceryl ferulate was synthesized. The reaction products were characterized using RP-HPLC, FTIR, ¹H NMR, ¹³C NMR and fluorescence spectrophotometry. The kinetic parameters of esterification reaction were determined according to ping-pong bi-bi model. The K_m and υ_max were found to be 69.37 and 3.46 mmol, and 0.387 and 1.02 mmol/(min·g) for glyceryl ferulate and feruloyl glyceryl linoleate, respectively. The kinetic parameters were simulated in MATLAB and the experimental data were in good agreement. Furthermore, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of the blend of feruloyl ester and palm oil was higher than of the plain palm oil and was closer to α-tocopherol.

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.

Co-expression of an organic solvent-tolerant lipase and its cognate foldase of Pseudomonas aeruginosa CS-2 and the application of the immobilized recombinant lipase

The genes of CS-2 lipase and its cognate foldase were cloned from Pseudomonas aeruginosa CS-2. A stop codon was not found in the lipase gene. The amino acid sequence deduced from the lipase gene from P. aeruginosa CS-2 showed 97.8%, 71.3%, and 71.2% identity with lipases from P. aeruginosa LST-03, P seudomonas mendocina ymp, and Pseudomonas stutzeri A1501, respectively. The co-expression of CS-2 lipase and its cognate foldase of P. aeruginosa CS-2 in E scherichia coli BL21 (DE3) resulted in the formation of a soluble lipase. The recombinant lipase and foldase were purified to homogeneity using nickel affinity chromatography and about 10.2-fold with 40.9% recovery was achieved for the purification of the recombinant lipase. The molecular masses of the lipase and the foldase were estimated to be 35.7 and 38.3 kDa in SDS-PAGE, respectively. The recombinant lipase showed stability in the presence of some organic solvents. The recombinant CS-2 lipase was immobilized and subsequently used for the synthesis of butyl acetate in heptane. The conversion of substrate decreased from 98.2% to 87.4% after 5 cycles in reuse of the immobilized lipase.

Synthesis of ethyl ferulate in organic medium using celite-immobilized lipase

In the present work we have evaluated synthesis of ethyl ferulate by the esterification reaction of ferulic acid and ethanol catalyzed by a commercial lipase (Steapsin) immobilized onto celite-545 in a short period of 6h in DMSO. The immobilized lipase was treated with cross-linking agent glutaraldehyde (1%; v/v). The optimum synthesis of ethyl ferulate was recorded at 45°C, pH 8.5 and 1:1 ratio of ethanol and ferulic acid. Co(2+), Ba(2+)and Pb(2+) ions enhanced the synthesis of ethyl ferulate Hg(2+), Cd(3+)and NH(4+) ions had mild inhibitory effect. The celite-bound lipase produced 68 mM of ethyl ferulate under optimized reaction conditions.