Peptide antibiotic production through immobilized biocatalyst technology

Overview of Immobilized Enzymes' Applications in Pharmaceutical, Chemical, and Food Industry

The use of immobilized enzymes in industry is becoming a routine process for the manufacture of many key compounds in the pharmaceutical, chemical, and food industry. Some enzymes like lipases are naturally robust and efficient, can be used for the production of many different molecules, and have found broad industrial applications. Some more specific enzymes, like transaminases, have required protein engineering to become suitable for applications in industrial manufacture. For all enzymes, the possibility to be immobilized and used in a heterogeneous form brings important industrial and environmental advantages such as simplified downstream processing or continuous process operations. Here, we present a series of large-scale applications of immobilized enzymes with benefits for the food, chemical, pharmaceutical, cosmetics, and medical device industries, some of them hardly reported before.

Isolation, characterization and identification of antibiofouling metabolite from mangrove derived Streptomyces sampsonii PM33

In this study, we report the production, bioassay guided isolation and identification of antibiofouling metabolite from mangrove derived actinobacterium, Streptomyces sampsonii (PM33). The actinobacterial strain PM33 yields maximum amount of antifouling compounds through agar surface fermentation. In optimization, carbohydrates such as glucose, fructose and xylose, are suitable for maximum production of the active compound. In addition, other compounds such as malt extract, glutamine, and sodium chloride concentrations (2.5, 5 and 7.5%) and parameters such as pH 7.0 and temperature range 30 °C to 40 °C enhanced the production of antifouling metabolite. The antifouling metabolite was extracted in ethyl acetate. TLC and bioautography was used to separate and detect the antifouling metabolite present in the crude extract. The physico chemical features revealed that the antifouling metabolite PM33 – B as taxifolin (C₁₅H₁₂O₇). The purified taxifolin was found to be active against biofouling bacteria, algal spore germination and mollusc foot adherence, respectively. Toxicity nature of taxifolin was also determined by adopting zebrafish embryos. The taxifolin isolated from mangrove-derived Streptomyces sampsonii PM33 is a promising candidate for the development of eco-friendly antifouling preparation.

Immobilization of Ulp1 protease on NHS-activated Sepharose: a useful tool for cleavage of the SUMO tag of recombinant proteins

OBJECTIVE

To fabricate an active and stable enzyme through covalent immobilization, a Ubl-specific protease (Ulp1) was used to cleave small ubiquitin-like modifier (SUMO) fusion proteins.

RESULTS

We immobilized Ulp1 on N-hydroxysuccinimide (NHS)-activated Sepharose with a coupling efficiency of 1.7 mg/ml. The immobilized Ulp1 maintains 95% substrate-cleavage ability and significantly enhances pH and thermal stability, especially can withstand pH of 10.5. Besides resistance against some small molecules, the immobilized Ulp1 can tolerate 15% (v/v) DMSO and 20% (v/v) ethanol. It can be reused for more than 15 batch reactions with 90% activity retention. This provides a fast purification system to quickly obtain cleaved recombinant proteins with 95% purity from cell lysates with the application of immobilized Ulp1.

CONCLUSIONS

Ulp1 used in immobilization form is a potentially useful tool for cleavage of SUMO-tagged proteins and may reduce time and cost of protein purification.

Theoretical study of adsorption of amino acids on graphene and BN sheet in gas and aqueous phase with empirical DFT dispersion correction

Suitability of BN nanosheet/graphene towards the adsorption of amino acids established by dispersion corrected DFT calculations.

Blocked bacteria escape by ATRP grafting of a PMMA shell on PVA microparticles

This paper reports on the preparation and characterization of living composites consisting of poly(vinylalcohol) (PVA) hydrogel microparticles with living bacteria and a shell of poly(methyl methacrylate) (PMMA). The grafting of the PMMA shell is accomplished in the presence of living bacteria by surface polymerization of PMMA using atom transfer radical polymerization (ATRP). The PMMA shell prevents the uncontrolled bacterial escape from the hydrogel microparticles, which otherwise marks a major problem of these composites. The encapsulation of microparticles with living bacteria by PMMA retards bacteria escape upon contact to water for >20 d. The functionality of the PMMA shell is proven both by the release of fluorescein in buffer and an altered release time of bacteria in buffer solution.

Purification, partial characterization, and covalent immobilization-stabilization of an extracellular α-amylase from Aspergillus niveus

An extracellular amylase secreted by Aspergillus niveus was purified using DEAE fractogel ion exchange chromatography and Sephacryl S-200 gel filtration. The purified protein migrated as a single band in 5 % polyacrylamide gel electrophoresis (PAGE) and 10 % sodium dodecyl sulfate (SDS-PAGE). The enzyme exhibited 4.5 % carbohydrate content, 6.6 isoelectric point, and 60 and 52 kDa molar mass estimated by SDS-PAGE and Bio-Sil-Sec-400 gel filtration column, respectively. The amylase efficiently hydrolyzed glycogen, amylose, and amylopectin. The end-products formed after 24 h of starch hydrolysis, analyzed by thin layer chromatography, were maltose, maltotriose, maltotetraose, and maltopentaose, which classified the studied amylase as an α-amylase. Thermal stability of the α-amylase was improved by covalent immobilization on glyoxyl agarose (half-life of 169 min, at 70 °C). On the other hand, the free α-amylase showed a half-life of 20 min at the same temperature. The optima of pH and temperature were 6.0 and 65 °C for both free and immobilized forms.

Entrapment of Saccharomyces cerevisiae and 3T3 fibroblast cells into blue light cured hydrogels

Hydrogels, containing yeast cells or fibroblast cells, were fabricated using blue light-induced polymerization technique. The cell-loaded prepolymer formulation was comprised of poly(ethyleneglycol) diacrylate (more than or equal to 50% v/v), 0.5 wt % Eosin Y and 0.5 wt % triethanolamine as the base oligomer, photo-initiator, and co-initiator, respectively. The two model cell lines, Saccharomyces cerevisiae and NIH 3T3 fibroblasts maintained high viability pre- and post-processing. Several bioassays have demonstrated the unaffected intracellular and extracellular activities of the cells entrapped within the hydrogels. Scanning electron microscopy confirmed the proliferation of S. cerevisiae cells that were entrapped and cultivated for 48 h in growth media, which validated the favorable microenvironment and nutrient transport in these gels. Upon entrapment, fibroblast cells remain viable upto 12 h, however they failed to attach within the crosslinked network, thus no further proliferation was observed. The tunable properties of this hydrogel system project it as a useful matrix for specialized biohybrids.

Immobilization of Mucor miehei Lipase onto Macroporous Aminated Polyethersulfone Membrane for Enzymatic Reactions

Immobilization of enzymes is one of the most promising methods in enzyme performance enhancement, including stability, recovery, and reusability. However, investigation of suitable solid support in enzyme immobilization is still a scientific challenge. Polyethersulfone (PES) and aminated PES (PES–NH₂) were successfully synthesized as novel materials for immobilization. Membranes with various pore sizes (from 10–600 nm) based on synthesized PES and PES–NH₂ polymers were successfully fabricated to be applied as bioreactors to increase the immobilized lipase performances. The influence of pore sizes, concentration of additives, and the functional groups that are attached on the PES backbone on enzyme loading and enzyme activity was studied. The largest enzyme loading was obtained by Mucor miehei lipase immobilized onto a PES–NH₂ membrane composed of 10% of PES–NH₂, 8% of dibutyl phthalate (DBP), and 5% of polyethylene glycol (PEG) (872.62 µg/cm²). Hydrolytic activity of the immobilized lipases indicated that the activities of biocatalysts are not significantly decreased by immobilization. From the reusability test, the lipase immobilized onto PES–NH₂ showed a better constancy than the lipase immobilized onto PES (the percent recovery of the activity of the lipases immobilized onto PES–NH₂ and PES are 97.16% and 95.37%, respectively), which indicates that this novel material has the potential to be developed as a bioreactor for enzymatic reactions.

pH dependence of penicillin amidase enantioselectivity for charged substrates

The pH dependence of E (enantiomeric ratio or enantioselectivity, a quantitative measure for enzyme stereospecificity) was studied for penicillin amidase catalysed hydrolysis of charged enantiomeric substrates. Theoretical analysis shows that a pH dependence can only be observed around the pK values of groups in the active site whose ionisation control the enzyme activity. For charged substrates that may perturb these pK values, a pH dependence of E is also expected. This was experimentally verified around these pK values. The S'(1)-stereospecificity of penicillin amidase was studied for the hydrolysis of the enantiomeric phenylacetyl-S/R-Phe and for the racemic phenylacetyl-S,R-PhG. The S(1)-stereospecificity was investigated for the hydrolysis of the enantiomeric S/R-PhG-NH(2). The observed pH modulation of E (more than 3-fold for the studied substrates in the pH range 4.5-9) was found to be a result of compensatory effects for binding and catalysis. The ratios k(cat, S)/k(cat,R) and K(m,S)/K(m,R) for the hydrolysis of the enantiomeric phenylacetyl-Phe were found to decrease from 1000 to 10 and from 0.1 to 0.01, respectively in the pH range 5-8. The dependence was stronger for the S'(1)- than for the S(1)-subsite. This is probably due to the stronger influence of the substrate carboxyl group in the S'(1)-subsite than that of the substrate amino group in the S(1)-subsite on the pK of the N-terminal Ser B1 that is essential for the activity. The observed pH dependence of E was used to discuss the importance of ground-state interactions for discrimination between enantiomers and for enzyme catalysis in general. The experimental results conform to the split site model according to which a better binding must not be fundamentally inhibitory.

On the merits of viable-cell immobilisation

Many advantages have been claimed over the years for the use of immobilised cells, both as enzyme systems and as whole viable cell systems for complete fermentation reactions. However, few of the claims have been fully substantiated, and may not even be entirely justified. Most research is involved with single applications and the best that can be hoped for is some evidence that immobilised cells in each of these individual cases display some advantage over the equivalent free cell system. The purpose of this review is to assess the merits of viable cell immobilisation in the light of published literature and to elucidate the underlying mechanisms. Particular attention is paid to the generally unanticipated, but widely observed enhanced stability of immobilised cell fermentation processes.