Immobilization of dextranase from Chaetomium erraticum

Hydroxyapatite: An Eco-Friendly Material for Enzyme Immobilization

Biocatalysis has emerged in the last decade as a valuable and eco-friendly tool in chemical synthesis, allowing in several instances to reduce or eliminate the use of hazardous reagents, environmentally dangerous solvents and harsh reaction conditions. Enzymes are indeed able to catalyse chemical transformations on non-natural substrates under mild reaction conditions, still maintaining their high chemo-, regio-, and stereoselectivity. Enzyme immobilization, i. e. the grafting of enzymes on solid supports, can be viewed as an enabling technology, as it allows a better control of the reaction and the recycling of the biocatalyst, thus rendering economically viable the use of expensive enzymes also on a large scale. To pursue a sustainable approach, the supports for enzyme immobilization should be eco-friendly and possibly renewable. This review highlights the use of hydroxyapatite (HAP), an inorganic biomaterial able to confer strength and stiffness to the bone tissue in animals, as carrier for enzyme immobilization. HAP is a cheap, non-toxic and biocompatible material, with high surface area and protein affinity. Different enzyme classes, immobilization strategies, and the use of diverse HAP-based supports will be discussed, underlining the immobilization conditions and the properties of the obtained biocatalysts.

The Screening and Identification of a Dextranase-Secreting Marine Actinmycete Saccharomonospora sp. K1 and Study of Its Enzymatic Characteristics

In this study, an actinomycete was isolated from sea mud. The strain K1 was identified as Saccharomonospora sp. by 16S rDNA. The optimal enzyme production temperature, initial pH, time, and concentration of the inducer of this actinomycete strain K1 were 37 °C, pH 8.5, 72 h, and 2% dextran T20 of medium, respectively. Dextranase from strain K1 exhibited maximum activity at 8.5 pH and 50 °C. The molecular weight of the enzyme was <10 kDa. The metal ions Sr2+ and K+ enhanced its activity, whereas Fe3+ and Co2+ had an opposite effect. In addition, high-performance liquid chromatography showed that dextran was mainly hydrolyzed to isomaltoheptose and isomaltopentaose. Also, it could effectively remove biofilms of Streptococcus mutans. Furthermore, it could be used to prepare porous sweet potato starch. This is the first time a dextranase-producing actinomycete strain was screened from marine samples.

Review on recent advances in the properties, production and applications of microbial dextranases

Dextranase is a type of hydrolase that is responsible for catalyzing the breakdown of high-molecular-weight dextran into low-molecular-weight polysaccharides. This process is called dextranolysis. A select group of bacteria and fungi, including yeasts and likely certain complex eukaryotes, produce dextranase enzymes as extracellular enzymes that are released into the environment. These enzymes join dextran's α-1,6 glycosidic bonds to make glucose, exodextranases, or isomalto-oligosaccharides (endodextranases). Dextranase is an enzyme that has a wide variety of applications, some of which include the sugar business, the production of human plasma replacements, the treatment of dental plaque and its protection, and the creation of human plasma replacements. Because of this, the quantity of studies carried out on worldwide has steadily increased over the course of the past couple of decades. The major focus of this study is on the most current advancements in the production, administration, and properties of microbial dextranases. This will be done throughout the entirety of the review.

Marine Bacterial Dextranases: Fundamentals and Applications

Dextran, a renewable hydrophilic polysaccharide, is nontoxic, highly stable but intrinsically biodegradable. The α-1, 6 glycosidic bonds in dextran are attacked by dextranase (E.C. 3.2.1.11) which is an inducible enzyme. Dextranase finds many applications such as, in sugar industry, in the production of human plasma substitutes, and for the treatment and prevention of dental plaque. Currently, dextranases are obtained from terrestrial fungi which have longer duration for production but not very tolerant to environmental conditions and have safety concerns. Marine bacteria have been proposed as an alternative source of these enzymes and can provide prospects to overcome these issues. Indeed, marine bacterial dextranases are reportedly more effective and suitable for dental caries prevention and treatment. Here, we focused on properties of dextran, properties of dextran—hydrolyzing enzymes, particularly from marine sources and the biochemical features of these enzymes. Lastly the potential use of these marine bacterial dextranase to remove dental plaque has been discussed. The review covers dextranase-producing bacteria isolated from shrimp, fish, algae, sea slit, and sea water, as well as from macro- and micro fungi and other microorganisms. It is common knowledge that dextranase is used in the sugar industry; produced as a result of hydrolysis by dextranase and have prebiotic properties which influence the consistency and texture of food products. In medicine, dextranases are used to make blood substitutes. In addition, dextranase is used to produce low molecular weight dextran and cytotoxic dextran. Furthermore, dextranase is used to enhance antibiotic activity in endocarditis. It has been established that dextranase from marine bacteria is the most preferable for removing plaque, as it has a high enzymatic activity. This study lays the groundwork for the future design and development of different oral care products, based on enzymes derived from marine bacteria.

An enzymatic membrane reactor for oligodextran production: Effects of enzyme immobilization strategies on dextranase activity

An enzymatic membrane reactor (EMR) with immobilized dextranase provides an excellent opportunity for tailoring the molecular weight (Mw) of oligodextran to significantly improve product quality. However, a highly efficient EMR for oligodextran production is still lacking and the effect of enzyme immobilization strategy on dextranase hydrolysis behavior has not been studied yet. In this work, a functional layer of polydopamine (PDA) or nanoparticles made of tannic acid (TA) and hydrolysable 3-amino-propyltriethoxysilane (APTES) was first coated on commercial membranes. Then cross-linked dextranase or non-cross-linked dextranase was loaded onto the modified membranes using incubation mode or fouling-induced mode. The fouling-induced mode was a promising enzyme immobilization strategy on the membrane surface due to its higher enzyme loading and activity. Moreover, unlike the non-cross-linked dextranase that exhibited a normal endo-hydrolysis pattern, we surprisingly found that the cross-linked dextranase loaded on the PDA modified surface exerted an exo-hydrolysis pattern, possibly due to mass transfer limitations. Such alteration of hydrolysis pattern has rarely been reported before. Based on the hydrolysis behavior of the immobilized dextranase in different EMRs, we propose potential applications for the oligodextran products. This study presents a unique perspective on the relation between the enzyme immobilization process and the immobilized enzyme hydrolysis behavior, and thus opens up a variety of possibilities for the design of a high-performance EMR.

Isomalto-Oligosaccharides Produced by EndodextranaseShewanellasp. GZ-7 From Sugarcane Plants

Oligosaccharides have important alimental and medical applications. Dextranase has been used to produce isomalto-oligosaccharides (IMOs). In this study, we isolated dextranase-producing bacteria from sugarcane-cultivated soil. Identification of the isolate based on its phenotypical, physiological, and biochemical characteristics, as well as 16S ribosomal deoxyribonucleic acid gene sequencing yielded Shewanella sp. strain GZ-7. The molecular weight of the dextranase produced by this strain was 100-135 kDa. The optimum temperature and pH for dextranase production were 40 °C and 7.5, respectively. The enzyme was found to be stable at the pH range of 6.0-8.0 and the temperature range of 20 °C-40 °C. Thin-layer chromatography and high-performance liquid chromatography of the enzymolysis products of the substrate confirmed the enzyme to be endodextranase. Under the optimal conditions, the ratio of IMOs could reach 91.8% of the hydrolyzate. The final products were found to efficiently scavenge the 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and superoxide anion radicals. In general, dextranase and hydrolyzates have high potential prospects for application in the future.

The Marine Catenovulum agarivorans MNH15 and Dextranase: Removing Dental Plaque

Dextranase, a hydrolase that specifically hydrolyzes α-1,6-glucosidic bonds, has been used in the pharmaceutical, food, and biotechnology industries. In this study, the strain of Catenovulum agarivorans MNH15 was screened from marine samples. When the temperature, initial pH, NaCl concentration, and inducer concentration were 30 °C, 8.0, 5 g/L, and 8 g/L, respectively, it yielded more dextranase. The molecular weight of the dextranase was approximately 110 kDa. The maximum enzyme activity was achieved at 40 °C and a pH of 8.0. The enzyme was stable at 30 °C and a pH of 5–9. The metal ion Sr²⁺ enhanced its activity, whereas NH⁴⁺, Co²⁺, Cu²⁺, and Li⁺ had the opposite effect. The dextranase effectively inhibited the formation of biofilm by Streptococcus mutans. Moreover, sodium fluoride, xylitol, and sodium benzoate, all used in dental care products, had no significant effect on dextranase activity. In addition, high-performance liquid chromatography (HPLC) showed that dextran was mainly hydrolyzed to glucose, maltose, and maltoheptaose. The results indicated that dextranase has high application potential in dental products such as toothpaste and mouthwash.

Characterization of an Alkaline GH49 Dextranase from Marine Bacterium Arthrobacter oxydans KQ11 and Its Application in the Preparation of Isomalto-Oligosaccharide

A GH49 dextranase gene DexKQ was cloned from marine bacteria Arthrobacter oxydans KQ11. It was recombinantly expressed using an Escherichia coli system. Recombinant DexKQ dextranase of 66 kDa exhibited the highest catalytic activity at pH 9.0 and 55 °C. kcat/Km of recombinant DexKQ at the optimum condition reached 3.03 s⁻¹ μM⁻¹, which was six times that of commercial dextranase (0.5 s⁻¹ μM⁻¹). DexKQ possessed a Km value of 67.99 µM against dextran T70 substrate with 70 kDa molecular weight. Thin-layer chromatography (TLC) analysis showed that main hydrolysis end products were isomalto-oligosaccharide (IMO) including isomaltotetraose, isomaltopantose, and isomaltohexaose. When compared with glucose, IMO could significantly improve growth of Bifidobacterium longum and Lactobacillus rhamnosus and inhibit growth of Escherichia coli and Staphylococcus aureus. This is the first report of dextranase from marine bacteria concerning recombinant expression and application in isomalto-oligosaccharide preparation.

The Adsorption of Dextranase onto Mg/Fe-Layered Double Hydroxide: Insight into the Immobilization

We report the adsorption of dextranase on a Mg/Fe-layered double hydroxide (Mg/Fe-LDH). We focused the effects of different buffers, pH, and amino acids. The Mg/Fe-LDH was synthesized, and adsorption experiments were performed to investigate the effects. The maximum adsorption occurred in pH 7.0 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer, and the maximum dextranase adsorption uptake was 1.38 mg/g (416.67 U/mg); histidine and phenylalanine could affect the adsorption. A histidine tag could be added to the protein to increase the adsorption significantly. The performance features and mechanism were investigated with X-ray diffraction patterns (XRD) and Fourier transform infrared spectra (FTIR). The protein could affect the crystal structure of LDH, and the enzyme was adsorbed on the LDH surface. The main interactions between the protein and LDH were electrostatic and hydrophobic. Histidine and phenylalanine could significantly affect the adsorption. The hexagonal morphology of LDH was not affected after adsorption.

Enzyme immobilization on cellulose matrixes

Enzymes are excellent catalysts in many applications due to their biocompatibility, low energy consumption, unique selectivity, and mild reaction condition. However, some disadvantages limit the usage of enzymes in end uses, such as low stabilities and difficult recovery. In order to overcome these disadvantages, enzyme immobilization was developed. Among various kinds of substrates for attaching enzyme, cellulose and its derivatives are one of the ideal matrixes because they are low cost, nontoxic, renewable, biodegradable, and biocompatible. In this review, we summarize recent progress in the research of enzyme immobilization on cellulose matrixes.

Purification, characterization and end product analysis of dextran degrading endodextranase from Bacillus licheniformis KIBGE-IB25

Degradation of high molecular weight dextran for obtaining low molecular weight dextran is based on the hydrolysis using chemical and enzymatic methods. Current research study focused on production, purification and characterization of dextranase from a newly isolated strain of Bacillus licheniformis KIBGE-IB25. Dextranase was purified up to 36 folds with specific activity of 1405 U/mg and molecular weight of 158 kDa. It was found that enzyme performs optimum cleavage of dextran (5000 Da, 0.5%) at 35 °C in 15 min at pH 4.5 with a Km and Vmax of 0.374 mg/ml and 182 μmol/min, respectively. Relative amino acid composition analysis of purified enzyme suggested the presence of higher number of hydrophobic, acidic and glycosylation promoting amino acids. The N-terminal sequence of dextranase KIBGE-IB25 was AYTVTLYLQG. It exhibited distinct amino acid sequence yet shared some inherent characteristics with glycosyl hydrolases (GH) family 49 and also testified the presence of O-glycosylation at N-terminal end.

Extending synthetic routes for oligosaccharides by enzyme, substrate and reaction engineering

The integration of all relevant tools for bioreaction engineering has been a recent challenge. This approach should notably favor the production of oligo- and polysaccharides, which is highly complex due to the requirements of regio- and stereoselectivity. Oligosaccharides (OS) and polysaccharides (PS) have found many interests in the fields of food, pharmaceuticals, and cosmetics due to different specific properties. Food, sweeteners, and food ingredients represent important sectors where OS are used in major amounts. Increasing attention has been devoted to the sophisticated roles of OS and glycosylated compounds, at cell or membrane surfaces, and their function, e.g., in infection and cancer proliferation. The challenge for synthesis is obvious, and convenient approaches using cheap and readily available substrates and enzymes will be discussed. We report on new routes for the synthesis of oligosaccharides (OS), with emphasis on enzymatic reactions, since they offer unique properties, proceeding highly regio- and stereoselective in water solution, and providing for high yields in general.

Ultrasound-assisted dextranase entrapment onto Ca-alginate gel beads

In this research work, dextranase has immobilized onto calcium alginate beads using a novel ultrasound method. The process of immobilization of the enzyme was carried out in a one-step ultrasound process. Effects of ultrasound conditions on loading efficiency and immobilization yield of the enzyme onto calcium alginate beads were investigated. Furthermore, the activity of the free and immobilized enzymes prepared with and without ultrasound treatment, as a function of pH, temperature, recyclability and enzyme kinetic parameters, was compared. The maximum loading efficiency and the immobilization yield were observed when the immobilized dextranase was prepared with an ultrasonic irradiation at 25 kHz, 40 W for 15 min, under which the loading efficiency and the immobilization yield increased by 27.21% and 18.77%, respectively, compared with the immobilized enzymes prepared without ultrasonic irradiation. On the other hand, immobilized enzyme prepared with ultrasonic irradiation showed Vmax and KM value higher than that for the immobilized enzyme prepared without ultrasonic irradiation, likewise, both the catalytic and specificity constants of immobilized enzyme prepared with ultrasonic irradiation were higher than that for immobilized enzyme prepared without ultrasound, indicating that, this new ultrasonic method improved the catalytic kinetics activity of immobilized dextranase at all the reaction conditions studied. Compared with immobilized enzyme prepared without ultrasound treatment, the immobilized enzymes prepared with ultrasound irradiation exhibited: a higher pH optimum, optimal reaction temperature, activation energy, and thermal stability, as well as, a higher recyclability, which, illustrating the effectiveness of the sonochemical method. To the best of our knowledge, this is the first report on the effect of ultrasound treatments on the immobilization of dextranase.

Immobilisation of a hydroperoxide lyase and comparative enzymological studies of the immobilised enzyme with membrane-bound enzyme

BACKGROUND

Hydroperoxide lyase is the key enzyme in lipoxygenase pathway producing green-note flavours and has potential value for the flavour additive industry. So far, only a low yield of green-note flavours produced by hydroperoxide lyase has been achieved, primarily because of its instability. The aim of this study was to stabilise hydroperoxide lyase from Amaranthus tricolor leaves by immobilisation and investigate the characteristics of immobilised enzyme in comparison with free and native membrane-bound enzyme.

RESULTS

A maximum activity of 2.85±0.1 U g(-1) (wet) ceramic hydroxyapatite and a yield of 80% were obtained under optimised coupling conditions. The optimal reaction pH was 6.0, 6.0 and 7.5 for free, membrane-bound and immobilised enzyme respectively, while the optimal reaction temperature was 30, 35 and 35 °C respectively. Thermal and operational stability of immobilised enzyme were substantially enhanced. However, a higher substrate diffusion resistance was imposed after immobilisation, as evidenced by the Km value of immobilised enzyme being higher than that of free and membrane-bound enzyme.

CONCLUSION

Ceramic hydroxyapatite was a candidate for the immobilisation of hydroperoxide lyase from A. tricolor leaves. The stability of hydroperoxide lyase was substantially improved after immobilisation on this substrate.

Stability Study of Crude Dextransucrase from Leuconostoc citreum NRRL B-742

In the present work, the stability of crude dextransucrase from Leuconostoc citreum B-742 was evaluated in synthetic and in cashew apple juice culture broth. Optimum stability conditions for dextransucrase from L. citreum B-742 were different from the reported for its parental industrial strain enzyme (L. mesenteroides B-512F). Crude dextransucrase, from L. citreum B-742, produced using cashew apple juice as substrate, presented higher stability than the crude enzyme produced using synthetic culture medium, showing the same behavior previously reported for dextransucrase from L. mesenteroides B-512F. The crude enzyme presented good stability in cashew apple juice for 48 h at 25°C and pH 6.5.

Metal sulfide nanoparticles synthesized via enzyme treatment of biopolymer stabilized nanosuspensions

Nanoparticles of CuS, Cu(x)S, Ag(2)S and CdS were successfully prepared using a novel general and green synthetic process to give dextran biopolymer stabilised metal sulfifde nanosuspensions. Following preparation, dextranase enzyme was used to remove the bulk of the bound dextran to give pure stable metal sulfide nanocrystals for application in for example aspects of medicine, photonics and solar cells. Particles of good homogeneity were obtained and the CuS nanoparticle size was controlled to 9-27 nm by adjusting the reaction conditions. Cu(2)S nanoparticles were 14 nm, Ag(2)S nanoparticles were 20-50 nm and CdS nanoparticles were 9 nm is size. The complexing mechanism of nanoparticle sulfides to dextrans was further studied using carboxylmethyl dextran as a complexing agent and crosslinked Sephadex (dextran) ;beads as substrate. Particles were characterized by TEM, XRD, TGA, FT-IR and zeta-potential measurement, and their UV-vis spectroscopic absorption properties were determined. Stabilization of the sulfide nanoparticles with soluble hydroxylated biopolymers such as dextran is previously unreported and is here interpreted in terms of viscosity, pH of the system and weak polar S-H or S(metal)OH(2)(+) interactions with dextran depending on the material. Notably, the complexing mechanism appears to differ significantly from that taking place in known dextran-metal oxide systems. The process shown here has good potential for scale-up as a biosynthetic route for a range of functional sulfide nanoparticles.