Carboxymethylcellulose and poly(vinyl alcohol) used as a film support for lipases immobilization

Antifungal activity of rapamycin on Botryosphaeria dothidea and its effect against Chinese hickory canker

BACKGROUND

The trunk canker caused by Botryosphaeria dothidea is a devastating disease for Chinese hickory (Carya cathayensis) in China. Chemical fungicides are commonly and repeatedly applied to control the disease; however, fungicide application raises major environmental and food safety issues. Ecofriendly biocontrol alternatives were urgently needed. Herein, the antifungal activity of a natural secondary metabolite, rapamycin, against B. dothidea and the effect of a rapamycin-producing Streptomyces hygroscopicus on C. cathayensis canker were investigated.

RESULTS

The 50% effective concentrations (EC₅₀ ) of rapamycin against mycelial growth and spore germination on the potato dextrose agar were 5.1 × 10^-3 and 5.5× 10^-2 μg mL^-1 , respectively, which were much lower than the EC₅₀ values of thiophanate-methyl. The hyphae of B. dothidea exhibited premature aging and wrinkling after treatment with rapamycin at 5.0 × 10^-3 μg mL^-1 . A rapamycin-producing bacterium S. hygroscopicus LYJ637 was batch produced and formulated in a carboxymethylcellulose/poly (vinyl alcohol) (CMC/PVA) blend and used for testing the efficiency of the bacterium in controlling Botryosphaeria canker in C. cathayensis. S. hygroscopicus exhibited high stability in the CMC/PVA blend. Results of a 3-year field experiment suggested that rapamycin formation reduced the occurrence of both developed cankers and new cankers, with an efficacy comparable to the treatment with thiophanate-methyl.

CONCLUSION

The rapamycin-producing S. hygroscopicus LYJ637 carried in a CMC/PVA blend prevented effectively Botryosphaeria canker on Chinese hickory, which provides an alternative approach to chemical control strategies.

Structural Study of (Hydroxypropyl)Methyl Cellulose Microemulsion-Based Gels Used for Biocompatible Encapsulations

(Hydroxypropyl)methyl cellulose (HPMC) can be used to form gels integrating a w/o microemulsion. The formulation in which a microemulsion is mixed with a hydrated HPMC matrix has been successfully used as a carrier of biocompatible ingredients. However, little is known about the structure of these systems. To elucidate this, scanning electron microscopy was used to examine the morphology and the bulk of the microemulsion-based gels (MBGs) and small-angle X-ray scattering to clarify the structure and detect any residual reverse micelles after microemulsion incorporation in the gel. Electron paramagnetic resonance spectroscopy was applied using spin probes to investigate the polar and non-polar areas of the gel. Furthermore, the enzyme-labelling technique was followed to investigate the location of an enzyme in the matrix. A structural model for HPMC matrix is proposed according to which, although a w/o microemulsion is essential to form the final gel, no microemulsion droplets can be detected after incorporation in the gel. Channels are formed by the organic solvent (oil), which are coated by surfactant molecules and a water layer in which the enzyme can be hosted.

Rhizopus oryzae Lipase, a Promising Industrial Enzyme: Biochemical Characteristics, Production and Biocatalytic Applications

Lipases are biocatalysts with a significant potential to enable a shift from current pollutant manufacturing processes to environmentally sustainable approaches. The main reason of this prospect is their catalytic versatility as they carry out several industrially relevant reactions as hydrolysis of fats in water/lipid interface and synthesis reactions in solvent-free or non-aqueous media such as transesterification, interesterification and esterification. Because of the outstanding traits of Rhizopus oryzae lipase (ROL), 1,3-specificity, high enantioselectivity and stability in organic media, its application in energy, food and pharmaceutical industrial sector has been widely studied. Significant advances have been made in the biochemical characterisation of ROL particularly in how its activity and stability are affected by the presence of its prosequence. In addition, native and heterologous production of ROL, the latter in cell factories like Escherichia coli, Saccharomyces cerevisiae and Komagataella phaffii (Pichia pastoris), have been thoroughly described. Therefore, in this review, we summarise the current knowledge about R. oryzae lipase (i) biochemical characteristics, (ii) production strategies and (iii) potential industrial applications.

Biodiesel Production via Trans-Esterification Using Pseudomonas cepacia Immobilized on Cellulosic Polyurethane

In this work, Pseudomonas cepacia lipase immobilized on cellulosic polyurethane was used as a catalyst for biodiesel production via trans-esterification reactions in order to provide cost-effective methods of enzyme recycling. The efficacy of the immobilized enzyme catalyst at low loading (6.2 wt %) and the effects of temperature, water content, and reaction time in model trans-esterification of glyceryl trioctanoate were investigated extensively. It was found that water was necessary for the reaction of glyceryl trioctanoate with ethanol to proceed. A high conversion of glyceryl trioctanoate (∼70%) was obtained at 35 °C, with only 5.0 wt % of water content over a reaction period of 12 h.

Immobilization of Thermomyces lanuginosus lipase on ZnO nanoparticles: mimicking the interfacial environment

In this study, we propose that enzyme activity on immobilization can be controlled and enhanced by providing the environment mimicking the lipid/water interface.

Penicillium expansum lipase-coated magnetic Fe3O4–polymer hybrid hollow nanoparticles: a highly recoverable and magnetically separable catalyst for the synthesis of 1,3-dibutylurea

Amino-epoxy supports were innovatively imported onto magnetic nanoparticles for immobilizing enzyme which represents a novel class of heterogeneous catalyst for the synthesis of 1,3-dibutylurea from ethylene carbonate and butylamine.

High productivity bioethanol fermentation by immobilized Saccharomyces bayanus onto carboxymethylcellulose-g- poly(N-vinyl-2-pyrrolidone) beads

Crosslinked graft copolymers of CMC with N-vinyl-2-pyrrolidone (N-VP) were prepared in different grafting yields. Saccharomyces bayanus was immobilized in the graft copolymers of carboxymethylcellulose-g-poly(N-vinyl-2-pyrrolidone) (CMC-g-PVP) for ethanol fermentation. The effects of grafting yield, initial glucose concentration, and crosslinker concentration on the yield of ethanol process was investigated. Ethanol production increased when percentage of N-vinyl-2-pyrrolidone in the graft copolymer was increased. The maximum concentration, productivity, and yield of ethanol were 98.78 g L (-1), 8.23 g L (-1) h (-1) and 0.494 g g (-1), respectively. Reusability of the immobilized yeasts was found that the materials can be used seven times without losing their activity.

Physical immobilization of Rhizopus oryzae lipase onto cellulose substrate: activity and stability studies

Rhizopus oryzae lipase (ROL) was immobilized by adsorption onto oxidized cellulose fibers and regenerated films. The maximum adsorption level increases with the raise in the amount of carboxylic groups on cellulose surface confirming that adsorption is being governed mainly by electrostatic interaction between the enzyme and the substrate. This hypothesis was further confirmed by zeta-potential measurements showing a decrease in the zeta-potential of the fibers after enzyme adsorption. XPS analysis showed an intensification of the N 1s peak attesting the presence of the enzyme on the surface. The effect of temperature, pH and solvent polarity on the immobilized enzyme activity and stability was investigated. The catalytic esterification of oleic acid with n-butanol has been carried on using hexane as an organic solvent. A high conversion yield was obtained (about 80%) at 37 degrees C with a molar ratio of oleic acid to butanol 1:1 and 150IU immobilized lipase. The adsorption achieved two successive cycles with the same efficiency, and started to lose its activity during the third cycle.