Extracellular lipase of Aspergillus niger NRRL3; production, partial purification and properties

Evaluation of wool protein hydrolysate as peptone for production of microbial enzymes

Peptones are one of the most expensive components of microbial culture media. The present study was conducted to test the usability of low-cost sheep wool peptone (SWP) as an organic nitrogen source in the production of six industrially important enzymes (lipase, amylase, tannase, pectinase, cellulase and invertase). SWP was prepared by alkaline hydrolysis and acid neutralization. Bacillus licheniformis and Aspergillus niger were selected as test microorganisms for enzyme production. To evaluate the efficacy of SWP in enzyme production, it was compared with commercial tryptone peptone (TP) in the shaking flask cultures of the test microorganisms. The optimum concentration of both SWP and TP was determined to be 8 g/L for the production of B. licheniformis-derived enzymes, but 6 g/L for the production of A. niger-derived enzymes. It was determined that SWP was superior to TP in the production of four enzymes (lipase, amylase, tannase and pectinase) of both B. licheniformis and A. niger. This is the first study about the usage of sheep wool protein hydrolysate (SWP) as an organic nitrogen source or a peptone in fermentative production of microbial enzymes.

Immobilized Lipase in Resolution of Ketoprofen Enantiomers: Examination of Biocatalysts Properties and Process Characterization

In this study, lipase from Aspergillus niger immobilized by physical immobilization by the adsorption interactions and partially interfacial activation and mixed physical immobilization via interfacial activation and ion exchange was used in the kinetic resolution of the ketoprofen racemic mixture. The FTIR spectra of samples after immobilization of enzyme-characteristic signals can be seen, and an increase in particle size diameters upon immobilization is observed, indicating efficient immobilization. The immobilization yield was on the level of 93% and 86% for immobilization unmodified and modified support, respectively, whereas activity recovery reached around 90% for both systems. The highest activity of immobilized biocatalysts was observed at pH 7 and temperature 40 °C and pH 8 and 20 °C for lipase immobilized by physical immobilization by the adsorption interactions and partially interfacial activation and mixed physical immobilization via interfacial activation and ion exchange, respectively. It was also shown that over a wide range of pH (from 7 to 10) and temperature (from 20 to 60 °C) both immobilized lipases retained over 80% of their relative activity, indicating improvement of enzyme stability. The best solvent during kinetic resolution of enantiomers was found to be phosphate buffer at pH 7, which obtained the highest efficiency of racemic ketoprofen methyl ester resolution at the level of over 51%, followed by enantiomeric excess 99.85% in the presence of biocatalyst obtained by physical immobilization by the adsorption interactions and partially interfacial activation.

Thermo-alkali-stable lipase from a novel Aspergillus niger: statistical optimization, enzyme purification, immobilization and its application in biodiesel production

The influences of nutritional components affecting lipase production from the new Aspergillus niger using wheat bran as substrate were studied by employing Plackett-Burman and central composite statistical designs. Out of the 11 medium components tested, sucrose, KH₂PO₄ and MgSO₄ at final concentrations of 3.0, 1.0 and 0.5 g/L, respectively, were reported to contribute positively to enzyme production (20.09 ± 0.98 U/g ds). The enzyme was purified through ammonium sulfate precipitation followed by Sephadex G-100 gel filtration. Molecular mass of the purified lipase was 57 kDa as evident on SDS-PAGE. Different methods of immobilization were studied and the highest immobilization yield of 81.7 ± 2.18% was reported with agarose (2%) and the optimum temperature was raised from 45 to 50 °C. Immobilized lipase could retain 80% of its original activity at 60 °C after 1 hr of incubation, and was stable at pH values between neutral and alkaline pH. Lipase-catalyzed transesterification process of fungal oil resulted in a fatty acid methyl ester yield consisting of a high percentage of polyunsaturated fatty acids (83.6%), making it appropriate to be used as winter-grade biodiesel. The operational stability studies revealed that the immobilized lipase could keep 70% of its total activity after 5 cycles of the transesterification process.

Molecular, physiological, and biochemical characterization of extracellular lipase production by Aspergillus niger using submerged fermentation

Background

Extracellular production of fungal lipases especially the lipases obtained from the Aspergilli has gained immense interest in recent years due to its diverse biotechnological applications. In this study, we focused on determining the fermentation parameters required for the optimal lipase production.

Methods

A total of 256 fungal isolates were obtained from oil seeds. From each genus, one isolate was selected to evaluate lipase production using phenol red and tributyrin plate assays. Lipase activity was estimated using the spectrophotometric pNPP hydrolysis assay. The highest lipase producer isolates were identified using 18S ribosomal RNA gene sequencing. The genetic variability was determined by random amplified polymorphic DNA (RAPD) analysis and the dendrogram was constructed using the unweighted pair group method with arithmetic averages method. The isolates were examined in a submerged fermentation culture (Smf) to measure the effect of temperature, pH, incubation time, carbon source, nitrogen source, inoculum volume, and lipid source on lipase production.

Results

Eleven isolates belonging to the genus Aspergillus were analyzed for lipase production where they were found to be the highest lipase producers among various fungal genera. All the tested isolates were identified as A. niger using 18s rRNA sequencing. Genetic diversity was evaluated among all of the studied A. niger isolates using RAPD primers. The RAPD primers were used to amplify 285 loci, of which five were polymorphic (1.75%) and seven were monomorphic (2.45%). Thus, a high level of genetic diversity was observed among all isolates. The tributyrin test and the lipase activity assay identified five strains of A. niger as high lipase producers, and their optimal enzyme activities were 709.74, 532.54, 735.64, 794.62, and 787.69 U/ml. The optimal conditions for lipase production were as follows: 40 °C, pH 7.5, 1% fructose as the carbon source, 1% yeast extract as the nitrogen source, 2% palm oil, 2.5 × 10⁷ spores/ml suspension, and 3 days of incubation.

Conclusions

The current study provides a comprehensive characterization of the optimal conditions, which are essential to enhance lipase production in five A. niger isolates.

Lipolytic Enzymes with Hydrolytic and Esterification Activities Produced by Filamentous Fungi Isolated from Decomposition Leaves in an Aquatic Environment

Microbial lipases are prominent biocatalysts able to catalyze a wide variety of reactions in aqueous and nonaqueous media. In this work, filamentous fungi isolated from leaves decomposed in an aquatic environment were screened for lipase production with hydrolytic activity and esterification. Agar plates with Tween 20 and Rhodamine B were used for selection, while submerged cultures with olive oil were subsequently used to select 38 filamentous fungi. Trichoderma harzianum, Fusarium solani, Trichoderma harzianum F5, and Penicillium sp. F36 were grown in six different culture media. F. solani presented the highest lipase production (2.37 U/mL) with esterification activity of 0.07 U/mL using medium composed of (g.L-1) KH2PO4 1.00, MgSO4 H2O 1.123, and CuSO4 0.06. Supplementation of this culture medium with organic nitrogen sources increased lipase production by 461.3% using tryptone and by 419.4% using yeast extract. Among the vegetable oils from the Amazon region, degummed cotton oil induced lipase production up to 8.14 U/mL. The lipase produced by F. solani F61 has great potential to application in conventional processes and biodiesel production by transesterification of vegetable oils, as well as food industries in the production of fatty acid esters by hydrolysis and esterification.

Functional Characterization of a Novel Marine Microbial Esterase and its Utilization in the Enantioselective Preparation of (R)-Methyl 2-Chloropropionate

Chiral 2-chloropropanoic acids and their ester derivatives are crucial intermediates in the synthesis of many chemicals, especially herbicides. The enzymatic synthesis of chiral 2-chloropropanoic acids and their ester derivatives by esterases was not easily achieved, because the structural difference between the two enantiomers was too small to be recognized by esterases. Herein, we report the expression and functional characterization of one novel low temperature-resistant esterase EST12-7 identified from the genome of Pseudonocardia antitumoralis SCSIO 01299 isolated from the sediments of the South China Sea. Biocatalyst EST12-7 could hydrolyze racemic methyl 2-chloropropinate and generate optically pure (R)-methyl 2-chloropropinate with high enantiomeric excess (>99 %) and conversion (>49 %) after process optimization. Notably, the addition of different surfactants and using surfactants of different concentrations in the kinetic resolution catalyzed by EST12-7 could greatly affect the enantiomeric excess and conversion rate of product (R)-methyl 2-chloropropinate.

Lipolytic potential of Aspergillus japonicus LAB01: production, partial purification, and characterisation of an extracellular lipase

Lipolytic potential of Aspergillus japonicus LAB01 was investigated by describing the catalytic properties and stability of a secreted extracellular lipase. Enzyme production was considered high under room temperature after 4 days using sunflower oil and a combination of casein with sodium nitrate. Lipase was partially purified by 3.9-fold, resulting in a 44.2% yield using ammonium sulphate precipitation (60%) quantified with Superose 12 HR gel filtration chromatography. The activity of the enzyme was maximised at pH 8.5, and the enzyme demonstrated stability under alkaline conditions. The optimum temperature was found to be 45°C, and the enzyme was stable for up to 100 minutes, with more than 80% of initial activity remaining after incubation at this temperature. Partially purified enzyme showed reasonable stability with triton X-100 and was activated in the presence of organic solvents (toluene, hexane, and methanol). Among the tested ions, only Cu²⁺, Ni²⁺, and Al³⁺ showed inhibitory effects. Substrate specificity of the lipase was higher for C14 among various p-nitrophenyl esters assayed. The K_M and V_max values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mM and 12.58 umol/(L·min), respectively. These features render a novel biocatalyst for industrial applications.

Overview of fungal lipase: a review

Lipases (triacylglycerolacyl hydrolases, EC3.1.1.3) are class of enzymes which catalyze the hydrolysis of long-chain triglycerides. In this review paper, an overview regarding the fungal lipase production, purification, and application is discussed. The review describes various industrial applications of lipase in pulp and paper, food, detergent, and textile industries. Some important lipase-producing fungal genera include Aspergillus, Penicillium, Rhizopus, Candida, etc. Current fermentation process techniques such as batch, fed-batch, and continuous mode of lipase production in submerged and solid-state fermentations are discussed in details. The purification of lipase by hydrophobic interaction chromatography is also discussed. The development of mathematical models applied to lipase production is discussed with special emphasis on lipase engineering.