Purification and characterization of a lipase from Aspergillus niger F044 / 生物工程学报

A lipase from Aspergillus niger F044 was purified to homogeneity using ammonium sulfate precipitation, dialysis, DEAE-Sepharose Fast Flow anion exchange chromatography and Sephadex G-75 gel filtration chromatography. This purification protocol resulted in a 73.71-fold purification of lipase with 33.99% final yield, and the relative molecular weight of the enzyme was determined to be approximately 35-40kD using SDS-PAGE. The optimum pH and temperature for lipolytic activity of the lipase was 7.0 and 45 degrees C , respectively. It was extremely stable at 60 degrees C and retained 98.70% of its original activity for 30min. The stability declined rapidly as soon as the temperature rose over 65 degrees C . The lipase was highly stable in the pH range from 2.0 to 9.0 for 4h. Ca2+ and Mg2+ ions stimulated lipolytic activity, whereas Mn2+ , Fe2+ and Zn2+ ions caused inhibition. The values of Km and Vmax calculated from the Lineweaver-Burk plot using pNPP as hydrolysis substrate were 7.37mmol/L and 25.91 micromol/(min x mg), respectively. The N-terminal sequence of the lipase was Ser/Glu/His-Val-Ser-Thr-Ser-Thr-Leu-Asp-Glu-Leu-Gln-Leu-Phe-Ala-Gln, which is highly homogeneity with that of lipase, as reported by Torossian.

Advances in Solid-state Fermentation of Microbial Lipase / 中国生物工程杂志

Lipases have catalytic active in both aqueous phase and the non-aqueous phase and have a wide range of application in various industrial areas.However,the high cost of lipase production has restricted its extensive use in industry.Solid state fermentation possesses many advantages,such as low requirement for devices,low energy consumption,low production cost,little pollution to environment and easily being popularized,which have made it an important means in microbial production of lipases.Owing to the rapidly increased energy cost and the people's awareness of environmental protection,the solid state fermentation technique,which was regarded as low-tech in the past,has regained attention and developed rapidly since the 1990s.The production of lipase by SSF technique was reviewed.Mainly contents describe its characteristics,including physical and chemical factors and bioreactors.

Optimization of Fermentation Conditions of Lipase Produced by Pseudomonas cepacia PCL-3 / 中国生物工程杂志

The fermentation conditions of alkaline lipase producing by Pseudomonas cepacia PCL-3 were optimized.Based on the analysis of single factorial experiments,dextrin was the most suitable carbon source,peptone and urea were the suitable compound nitrogen sources among the examined materials.Three significant factors(urea,inoculum and initial pH) were selected from the eight factors related to lipase production by Plaekett-Burman method,and were further optimized with response surface analysis.And then,steepest ascent procedures were applied to define the optimal response region of the three factors.The obtained optimal conditions were urea 0.15%,inoculum 3.05% and initial pH 8.38,under which conditions,the enzyme activity was improved from 25.37 U/ml to 48.88 U/ml,enhanced 1.93 folds.Starting from the flask conditions,the highest lipase activity of 47.69U/ml was achieved by batch fermentation in a 10 L fermentor after 52 h of the cultivation.

Effect of Bioimprinting by Lauric Acid on Esterification Activity of Lipase / 中国生物工程杂志

Bioimprinting is a new developed technique to improve the characteristics of enzymes.Bioimprinting by lauric acid was conducted to improve the esterification activity of lipase PS in sol-gel immobilization process with methyltrimethoxysila(MTMS) and tetramethoxysila(TMOS) as the precursors.Results generated by checking the esterification activity and scanning electron microscope showed that bioimprinting can enhance the specific activity and thermal stability of lipase PS.The bioimprinting system was optimized by orthogonal experiment,and the optimal condition for lipase bioimprinting is water/silane molar ration(R) 12,polyethylene glycol(PEG) 120?l,and lauric acid 0.15 mmol.Compared with the free enzyme and the non-imprinted enzymes,the specific activity of imprinted enzymes has been improved 44.3 fold and 2.4 fold,respectively.Imprinted lipase show better thermal stability,and the relative activity is 58% after incubated in 80 ℃ for 0.5 h,while no activity was detected for the free enzyme.

Research Advance in Recombinant Expression of Microbial Lipases / 中国生物工程杂志

Microbial lipases have been widely used in traditional industries,as well as in emerging biocatalysed areas owing to their ability to catalyze a variety of reactions in aqueous and non-aqueous media.Therefore,it is very important to enhance amount of lipase production by recombinant overexpression for meeting market demand.A critical review of main and novel strategies which have been employed for recombinant expression of microbial lipases are presented,including codon optimization,fusion and co-expression,dual expression system based on hybrid promoters,homologous overexpression,cell surface displaying and high-throughput screening based on gene library of expression.These new technologies are gradually coming to the forefront in the recombinant expression of lipase,especially for cell surface displaying and high-throughput screening based on gene library of expression.Meanwhile,several recombinant expressions for representative microbial lipases were also introduced and discussed,which are available for consultation when attempting to overexpress any lipases by scientists and industrialists.

Immobilized Lipases Cooperates to Catalyze Transesterification Reaction of Lard / 中国生物工程杂志

The transesterification reaction conditions of lard with methyl acetate with combined use of immobilized lipases as catalysts were conducted. Initially, according to single factorial experiments, the studies on Lipozyme TL IM and Novozym 435 respectively catalyzed transesterification of lard showed that the optimal parameters of transesterification reaction were: the molar ratio of methyl acetate to oil of 14∶1, 40% enzyme added based on oil weight, temperature 50℃. Combined use of Lipozyme TL IM and Novozym 435 was proposed further to improve the catalytic performance by the response surface method (RSM). Herein, a 5-level-3-factor central composite rotated design was employed to evaluate the effects of lipase loading, the proportion of the two lipases and amount of methyl acetate. The optimum conditions were as followings: 40% lipase loading based on oil weight, 50%/50% the proportion of lipases (Novozym 435/Lipozyme TL IM), and the molar ratio of methyl acetate to oil of 14∶1. And under the optimal conditions, the highest biodiesel yield of 97.6% could be attained, which was higher than the biodiesel yield with each single one of the two lipases. The results suggested that the technics of combined use of certain immobilized lipases catalyzed transesterification reaction of lard for biodiesel production with methyl acetate as the acyl acceptor could raise the FAME yield and save the production cost.

Optimization of Lipase Production Conditions by Geotrichum candidum Y162 Using Single Factor-response Surface Methodology / 中国生物工程杂志

The fermentation conditions of lipase production by Geotrichum candidum Y162 were optimized. Initially, the most suitable carbon olive oil, nitrogen source soybean flour and NH4Cl, salt BaCl2 and MgCl2 were selected according to single factorial experiments respectively. Based on the result, screening methodology Plackett-Burman design was used to evaluate the effects of twelve factors related to lipase production and three statistically significant factors olive oil, BaCl2 and NH4Cl were selected. The path of steepest ascent was used to approach the optimal region of lipase production subsequently. Then, the optimal combined concentration for maximum enzyme activity were further optimized by response surface methodology and determined as follows: olive oil 2.35%, BaCl2 0.36%,and NH4Cl 4.69%.The optimization of culture conditions of G.candidum Y162 led to a 2.25-fold increase in lipase production relative to initial result 14.16 U/ml, which indicate that single factor in combination with response surface methodology is an effective method for optimization of lipase production conditions by G.candidum Y162.

Aspergillus niger F044 Lipase:Gene Cloning,Overexpression and in vitro Refolding / 微生物学通报

From the N-terminal amino acid sequence of the Aspergillus niger F044 lipase,a potential homologous gene A84689 to the anl(the gene encoding the Aspergillus niger lipase)was found by means of bioinformatics.Based on the nucleotide sequence of the A84689,primers were designed to amplify anl.Nucleotide sequencing of the genomic anl gene revealed an open reading frame of 1 044 nucleotides,containing three introns(54,45 and 51 nucleotides).The deduced amino acid sequence of the anl gene corresponds to 297 amino acid residues including a signal sequence of 27 amino acid residues.The cloned cDNA coding for mature Anl(the protein of the Aspergillus niger lipase)was overexpressed in Escherichia coli BL21(De3),and the recombinant Anl was purified.The denatured recombinant Anl by 8mol/L urea was refolded in vitro by dilution and DEAE Sepharose Fast Flow chromatography.