Comparative study of the hydrolysis of different oils by lipase-immobilized membranes

Ultrasound-assisted production of biodiesel using engineered methanol tolerant Proteus vulgaris lipase immobilized on functionalized polysulfone beads

In the present study, Proteus vulgaris lipase (PVL) was engineered using directed evolution to increase methanol tolerance so that it would be more tolerant and efficient for harsh conditions employed in biodiesel synthesis, which is limiting their industrial use. The influence of ultrasound under different experimental conditions on the biodiesel conversion yield using methanolysis of non-edible neem oil was also emphasized. A special attention was also paid to the immobilization of lipase on Polysulfone (PS) beads and comparative studies with industrially used Burkholderia cepacia lipase. The Engineered Proteus vulgaris lipase showed >80% activity after 3 h when incubated in 50% methanol with simultaneous sonication. The lipase retained improved longevity (~70% residual activity) over wild-type PVL over repeated use.

High-level expression of lipase from Galactomyces geotrichum mafic-0601 by codon optimization in Pichia pastoris and its application in hydrolysis of various oils

A Galactomyces geotrichum strain with lipolytic activity was isolated and identified by the analysis of internal transcribed spacer (ITS) sequence of 18 s rDNA. Full-length lipase gene of this stain is composed of 1692 base pairs (bp) without intron, which encodes a 563-amino-acid protein. A catalytic triad (Ser²¹⁷-Glu³⁵⁴-His⁴⁶³) was found by constructing the three-dimensional structure of the lipase. In shake flasks, the lipase (LIP) catalytic activity in the supernatant of the recombinant Pichia pastoris increased 48.7% by codon optimization. LIP purified by anion exchange column showed a single protein band on 12% SDS-PAGE. The molecular weight (MW) of LIP was approximately 62 kDa. The specific activity of purified LIP reached 1257.9 U/mg. The optimum temperature and pH of LIP catalysis were 45 °C and pH 8.2, respectively. LIP was stable over the pH range of 4.2-11.2. LIP maintained its activity constantly at 40 °C and 50 °C for 120 min. Zn²⁺ inhibited LIP activity; Ba²⁺, Mn²⁺, Ca²⁺ and EDTA increased the enzyme activity. Referring the amount of hydrolyzed olive oil by LIP as 100%, various oils including lard, peanut oil, rapeseed oil, sunflower oil, soybean oil and linseed oil were efficiently hydrolyzed by 17.24 ± 1.34%, 40.34 ± 2.56%, 105.86 ± 2.78%, 115.51 ± 2.32%, 116.21 ± 2.15%, 120.69 ± 1.98%, respectively. The characteristics allow LIP as a potential biocatalyst in various fields of industry.

Fabrication and Optimization of a Lipase Immobilized Enzymatic Membrane Bioreactor based on Polysulfone Gradient-Pore Hollow Fiber Membrane

Enzymatic membrane bioreactors (EMBRs) possess the characteristic of combining catalysis with separation, and therefore have promising application potentials. In order to achieve a high-performance EMBR, membrane property, as well as operating parameters, should give special cause for concerns. In this work, an EMBR based on hollow fiber polysulfone microfiltration membranes with radial gradient pore structure was fabricated and enzyme immobilization was achieved through pressure-driven filtration. Lipase from Candida rugosa was used for immobilization and EMBR performance was studied with the enzymatic hydrolysis of glycerol triacetate as a model reaction. The influences of membrane pore diameter, substrate feed direction as well as operational parameters of operation pressure, substrate concentration, and temperature on the EMBR activity were investigated with the production of hydrolysates kinetically fitted. The complete EMBR system showed the highest activity of 1.07 × 104 U⋅g−1. The results in this work indicate future efforts for improvement in EMBR.

Recent advances in carbon nanotube based electrochemical biosensors

There is an increasing need for rapid, low cost, reusable, reliable and sensitive detection systems for diagnosing infectious diseases, metabolic disorders, rapidly advancing cancers and detecting the presence of environmental pollutants. Most traditional methods are invasive, slow, expensive and laborious, requiring highly specialized instruments. Introduction of biosensors with nanomaterials as transducers of signals have helped in removing the disadvantages associated with traditional detectors. The properties of high mechanical strength, better electrical conductivity and ability to serve as efficient signal transducers make carbon nanotubes (CNTs) ideal material for biosensor applications among the gamut of nanomaterials. Further, CNTs with their high surface areas, easily functionalizable surfaces for receptor immobilization are gaining importance in the construction of biosensors. The expanding field of CNTs bridges the physical sciences with biology, as chemical methods are employed to develop novel tools and platforms for understanding biological systems, in disease diagnosis and treatment. This review presents recent advances in surface functionalization of CNTs necessary for immobilization of enzymes and antibodies for biosensor applications and the methodologies used for the detection of a number of chemical and biological species. The review ends with a speculation on future prospects for CNTs in biology and medicine.

Combi-lipase for heterogeneous substrates: a new approach for hydrolysis of soybean oil using mixtures of biocatalysts

The concept of thecombi-lipasebiocatalyst has been proposed. It is based on the combination of different lipases as biocatalysts in reactions using heterogeneous substrates.