Effects of organic solvents on lipase for fat splitting

Molecular characterization of plant growth-promoting vermi-bacteria associated with Eisenia fetida gastrointestinal tract

Earthworms are highly productive invertebrates and play a vital role in organic farming and improving soil structure and function. The gastrointestinal tract of earthworms possessed agricultural important bacteria. So, the current research aimed was to examine, screen, and identify the plant growth promoting bacteria existing in the digestive tract of Eisenia fetida called plant growth promoting vermi-bacteria. The plant growth promoting traits such as siderophore, phytohormone, and hydrolytic enzymes production, and phosphate solubiliation were assessed. Eleven vermi-bacteria i.e. Bacillus mycoides, B. aryabhattai, B. megaterium, Staphylococcus hominis, B. subtilis, B. spizizenii, B. licheniformis, B. mojavensis, B. toyonensis, B. anthracis, B. cereus, B. thuringiensis, and B. paranthracis were isolated and identified based on microscopic studies, biochemical tests, ribotyping, and agricultural traits. All vermi-bacteria are Gram-positive rods except Staphylococcus hominis and produce different compounds such as siderophore, indole acetic acid, catalase, oxidase, proteases, amylases, and lipases. All vermi-bacteria also act as phosphate solubilizers. Therefore, all isolated vermi-bacteria could be used as potential microbial biofertilizers to enhance crops production in Pakistan.

Biocatalytic Synthesis of Natural Green Leaf Volatiles Using the Lipoxygenase Metabolic Pathway

In higher plants, the lipoxygenase enzymatic pathway combined actions of several enzymes to convert lipid substrates into signaling and defense molecules called phytooxylipins including short chain volatile aldehydes, alcohols, and esters, known as green leaf volatiles (GLVs). GLVs are synthesized from C18:2 and C18:3 fatty acids that are oxygenated by lipoxygenase (LOX) to form corresponding hydroperoxides, then the action of hydroperoxide lyase (HPL) produces C6 or C9 aldehydes that can undergo isomerization, dehydrogenation, and esterification. GLVs are commonly used as flavors to confer a fresh green odor of vegetable to perfumes, cosmetics, and food products. Given the increasing demand in these natural flavors, biocatalytic processes using the LOX pathway reactions constitute an interesting application. Vegetable oils, chosen for their lipid profile are converted in natural GLVs with high added value. This review describes the enzymatic reactions of GLVs biosynthesis in the plant, as well as the structural and functional properties of the enzymes involved. The various stages of the biocatalytic production processes are approached from the lipid substrate to the corresponding aldehyde or alcoholic aromas, as well as the biotechnological improvements to enhance the production potential of the enzymatic catalysts.

The kinetic behaviour of a two-enzyme system in biphasic media: coupling hydrolysis and lipoxygenation

Analysis of the kinetic behaviour of a two-enzyme-system carrying out two consecutive reactions was investigated in macroheterogeneous biphasic media (octane/buffer pH 9.6, v/v = 1:1). The lipase-catalysed hydrolysis of trilinolein and the subsequent lipoxygenation of the liberated linoleic acid, were coupled in a modified Lewis cell with a well-defined liquid/liquid interfacial area. Trilinolein was dissolved in the organic phase and hydrolysed in the presence of Mucor javanicus lipase at the organic/aqueous interface. Linoleic acid, liberated after hydrolysis was transferred to the aqueous phase and reacted with lipoxygenase. This reaction consumed linoleic acid and produced hydroperoxides, which favoured the transfer of residual linoleic acid, since they possess surface active properties. Catalysis and transfer influenced each other reciprocally. At low substrate concentrations, cooperativity phenomena were observed in the experimental and also the modelled two-enzyme systems. When the initial substrate concentration was high, the kinetic behaviour of the two-enzyme system in a compartmentalised medium, seemed to be independent of the substrate concentration, unlike that observed in homogeneous monophasic enzymology. The numerical integration program used to model the two-enzyme system was based on results obtained in separate studies of the following three phenomena: (1) trilinolein hydrolysis in biphasic medium. (2) linoleic acid transfer across a liquid/liquid interface and (3) lipoxygenation in an aqueous media. Results obtained by modelling were similar to the results observed experimentally.

Enzyme function in organic solvents

Enzyme catalysis in organic solvents is being increasingly used for a variety of applications. Of special interest are the cases in which the medium is predominantly non-aqueous and contains little water. A display of enzyme activity, even in anhydrous solvents (water less than 0.02% by vol.), perhaps reflects that the minimum necessity for water is for forming bonds with polar amino acids on the enzyme surface. The rigidity of enzyme structure at such low water content results in novel substrate specificities, pH memory and the possibility of techniques such as molecular imprinting. Limited data indicates that, while enhanced thermal stability invariably results, the optimum temperature for catalysis may not change. If true in general, this enhanced thermostability would have extremely limited benefits. Medium engineering and biocatalyst engineering are relevant techniques to improve the efficiency and stability of enzymes in such low water systems. Most promising, as part of the latter, is the technique of protein engineering. Finally, this review provides illustrations of applications of such systems in the diverse areas of organic synthesis, analysis and polymer chemistry.

Biocatalysis in multi-phase reaction mixtures containing organic liquids

A wide range of enzymes and whole microbial cells will act as catalysts in reaction mixtures that contain 2 or more phases, one of which is an organic liquid (either a reactant or including water-immiscible organic solvents). These "biphasic" systems have a variety of structures, knowledge of which aids predictions about biocatalyst activity and stability. There is often a dilute aqueous solution phase (containing the biocatalyst), which may be emulsified with the organic phase, or "trapped" within catalyst particles; sometimes however there may only be traces of water adsorbed to the enzyme or cells. These reaction systems offer several advantages for industrial applications, notably the higher solubilities of many reactants of interest, and the ability of readily available hydrolytic enzymes to catalyse syntheses. The most non-polar organic liquids are least likely to inactivate biocatalysts, though many do remain active with relatively polar solvents. Modification of the biocatalyst may stabilise against inactivation, especially where this is due to direct contact with the phase interface. The mass transfer processes required in these systems remain poorly understood, particularly because the interfacial area is often unknown. Attractive continuous reactors may be operated using a packed bed of catalyst with a trapped aqueous phase.