A novel method for covalent immobilization of dextransucrase

Coculture of bacterial levans and evaluation of its anti-cancer activity against hepatocellular carcinoma cell lines

This research represents a novel study to assess how coculture affects levan yield, structure, bioactivities, and molecular weight. Among the 16 honey isolates, four bacterial strains recorded the highest levan yield. The Plackett-Burman design showed that the coculture (M) of isolates G2 and K2 had the maximum levan yield (52 g/L) and the effective factors were sucrose, incubation time, and sugarcane bagasse. The CCD showed that the most proper concentrations for maximum levan yield (81 g/L): were 130 g/L of sucrose and 6 g/f of sugarcane bagasse. Levan's backbone was characterized, and the molecular weight was determined. G2 and K2 isolates were identified based on 16 sRNA as Bacillus megaterium strain YM1C10 and Rhizobium sp. G6-1. M levan had promising antioxidant activity (99.66%), slowed the migration activity to a great extent, and recorded 70.70% inhibition against the hepatoblastoma cell line (HepG2) at 1000 µg/mL. Gene expression analysis in liver cancer cell lines (HePG2) revealed that M levan decreased the expression of CCL20), 2GRB2, and CCR6) genes and was superior to Doxo. While increasing the expression of the IL4R and IL-10 genes. The DNA damage values were significantly increased (P < 0.01) in treated liver cancer cell lines with levan M and Doxo. The results referred to the importance of each of the hydroxyl and carboxyl groups and the molecular weight in levans bioactivities.

Prebiotic-mediated gastroprotective potentials of three bacterial levans through NF-κB-modulation and upregulation of systemic IL-17A

This study aimed to investigate whether the gastroprotective effects of three types of bacterial levans are correlated with their prebiotic-associated anti-inflammatory/antioxidant potentials. Three levans designated as LevAE, LevP, and LevZ were prepared from bacterial honey isolates; purified, and characterized using TLC, NMR, and FTIR. The anti-inflammatory properties of levan preparations were assessed in LPS-stimulated RAW 264.7 cell lines, while their safety and gastroprotective potentials were assessed in Wistar rats. The three levans significantly reduced ulcer number (22.29-70.05 %) and severity (31.76-80.54 %) in the ethanol-induced gastric ulcer model compared to the control (P < 0.0001/each), with the highest effect observed in LevAE and levZ (200 mg/each) (P < 0.0001). LevZ produced the highest levels of glutathione; catalase activity, and the lowest MDA levels (P = 0.0001/each). The highest anti-inflammatory activity was observed in LevAE and levZ in terms of higher inhibitory effect on IL-1β and TNF-α production (P < 0.0001 each); COX2, PGE2, and NF-κB gene expression. The three levan preparations also proved safe with no signs of toxicity, with anti-lipidemic properties as well as promising prebiotic activity that directly correlated with their antiulcer effect. This novel study highlights the implication of prebiotic-mediated systemic immunomodulation exhibited by bacterial levans that directly correlated with their gastroprotective activity.

Optimization strategy of Bacillus subtilis MT453867 levansucrase and evaluation of levan role in pancreatic cancer treatment

Pancreatic cancer is the fourth most lethal cancer type worldwide. Due to multiple levan applications including anticancer activities, studies related to levansucrase production are of interest. To our knowledge, levan effect on pancreatic cancer cells has not been tested previously. In this work, among eighteen bacterial honey isolates, Bacillus subtilis MT453867 showed the highest levan yield (33 g/L) and levansucrase production (8.31 U/mL). One-factor-at-a-time technique increased levansucrase activity by 60% when MgSO₄ was eliminated. The addition of 60 g/L banana peels enhanced the enzyme activity (192 U/mL). Placket Burman design determined the media composition for maximum levan yield (54.8 g/L) and levansucrase production (505 U/mL). The identification of levan was confirmed by thin-layer chromatography, Fourier-Transform Infrared spectrometric analysis, ¹³C-nuclear-magnetic resonance, and ¹H-nuclear-magnetic resonance. Both crude and dialyzed levan completely inhibited the pancreatic cancer cell line at 100 ppm with no cytotoxicity on the normal retinal cell line. The LD₅₀ of crude levan was 4833 mg/kg body weight. Levan had strong antioxidant activity and significantly reduced the expression of CXCR4 and MCM7 genes in pancreatic cancer cells with significant DNA fragmentation. In conclusion, Bacillus subtilis MT453867 levan is a promising adjunct to pancreatic-anticancer agents with both anti-cancer and chemoprotective effects.

Different strategies to co-immobilize dextransucrase and dextranase onto agarose based supports: Operational stability study

Co-immobilization is a groundbreaking technique for enzymatic catalysis, sometimes strategic, as for dextransucrase and dextranase. In this approach, dextranase hydrolytic action removes the dextran layer that covers dextransucrase reactive groups, improving the immobilization. Another advantage is the synergic effect of the two enzymes towards prebiotic oligosaccharides production. Thus, both enzymes were co-immobilized onto the heterobifunctional support Amino-Epoxy-Glyoxyl-Agarose (AMEG) and the ion exchanger support monoaminoethyl-N-ethyl-agarose (Manae) at pH 5.2 and 10, followed or not by glutaraldehyde treatment. This work is the first attempt to immobilize dextransucrase under alkaline conditions. The immobilized dextransucrase on AMEG support at pH 10 (12.78 ± 0.70 U/g) presents a similar activity of the biocatalyst produced at pH 5.2 (14.95 ± 0.82 U/g). The activity of dextranase immobilized onto Manae was 5-fold higher than the obtained onto AMEG support. However, the operational stability test showed that the biocatalyst produced on AMEG at pH 5.2 kept >60% of both enzyme activities for five batches. The glutaraldehyde treatment was not worthwhile to improve the operational stability of this biocatalyst.

Microbiological and environmental assessment of human oral dental plaque isolates

Plaque-related diseases are amongst the most common ailments of the oral cavity. Streptococcus mutans is the causal agent of dental caries in animals and humans and is responsible for the formation and accumulation of plaques. This study aimed to identify and evaluate the role of the dental plaque isolates and its surrounding environment in plaque formation or inhibition. The study started with the identification of human dental plaque isolates from high caries index patients based on 16S rRNA and Mitis salivarius bacitracin agar (MSB) was used for S. mutans growing. Unexpectedly, the Streptococcus mutans was completely absent. The disc diffusion assay recorded that all the isolates had antimicrobial activity against the S. mutans growth. Enzymes assay revealed that the isolates produced dextransucrase, levansucrase and levanase activity with wide variation degrees. Also, the lactic acid production assay was done based in pH shift assessment. The highest pH shift and dextran yield were detected by the isolates Bacillus subtilis_AG1 and Bacillus mojavensis_AG3. The adherence test revealed that Lysinibacillus cresolivorans_W2 (MK411028) recorded the highest adhesion property (60%). Oligo- and polysaccharides were synthesized by the action of dextransucrase enzyme and their cytotoxicity tests were negative. Dextran with a molecular weight (117521 Da) recorded the highest antimicrobial efficacy against Bacillus subtilis_AG1 and Bacillusmojavensis_AG3 (65%, 63.5%) respectively. The results concluded that the dextran was the most important factor causing the dental plaque pathogenicity. Also, oral oligo- and polysaccharides might play a role in dental plaque control.

Efficient Production of Prebiotic Gluco-oligosaccharides in Orange Juice Using Immobilized and Co-immobilized Dextransucrase

Dextransucrase from Leuconostoc mesenteroides NRRL B-512F was subjected to immobilization and co-immobilization with dextranase from Chaetomium erraticum. Immobilization has enhanced the operational and storage stability of dextransucrase. Two hundred milligrammes (2.4 IU/mg) of alginate beads (immobilized and co-immobilized) were found to be optimum for the production of gluco-oligosaccharides (GOS) in orange juice with a high degree of polymerization. The pulp of the orange juice did not interfere in the reaction. In the batch process, co-immobilized dextransucrase (41 g/L) produced a significantly higher amount of GOS than immobilized dextransucrase (37 g/L). Alginate entrapment enhanced the thermal stability of dextransucrase for up to 3 days in orange juice at 30 °C. The production of GOS in semi-continuous process was 39 g/L in co-immobilized dextransucrase and 33 g/L in immobilized dextransucrase. Thus, immobilization technology offers a great scope in terms of reusability and efficient production of a value added functional health drink.

Immobilization of Glycoside Hydrolase Families GH1, GH13, and GH70: State of the Art and Perspectives

Glycoside hydrolases (GH) are enzymes capable to hydrolyze the glycosidic bond between two carbohydrates or even between a carbohydrate and a non-carbohydrate moiety. Because of the increasing interest for industrial applications of these enzymes, the immobilization of GH has become an important development in order to improve its activity, stability, as well as the possibility of its reuse in batch reactions and in continuous processes. In this review, we focus on the broad aspects of immobilization of enzymes from the specific GH families. A brief introduction on methods of enzyme immobilization is presented, discussing some advantages and drawbacks of this technology. We then review the state of the art of enzyme immobilization of families GH1, GH13, and GH70, with special attention on the enzymes β-glucosidase, α-amylase, cyclodextrin glycosyltransferase, and dextransucrase. In each case, the immobilization protocols are evaluated considering their positive and negative aspects. Finally, the perspectives on new immobilization methods are briefly presented.

Enzymatic synthesis using immobilized Enterococcus faecalis Esawy dextransucrase and some applied studies

Dextrans enzymatic synthesis by immobilized Enterococcus faecalis Esawy dextransucrase was studied. Different parameters, such as: enzyme protein concentration (EPC), substrate concentration (SC), temperature and reaction time were evaluated. EPC played a fundamental role in controlling dextran molecular size with 0.1% dextran in reaction mixture. Dextran 38,397 and 125,471Da were yielded at EPC 4.78 and 5.78mg, respectively. Proper dextrans (73,378 and 117,521Da) demanded in pharmaceutical applications were achieved at 6% and 12% sucrose concentrations and at 4.78 and 5.78mg EPC, respectively. Optimum temperature for conversion of glucose to dextran was 30°C (73% and 80% at 5.78 and 4.78mg EPC, respectively). Varieties of maltooligosaccharides (MOS) were yielded by synergistic cooperation between sucrose and maltose. Six MOS and three dextrans samples in vitro have prebiotic effect on Lactobacillus casei with degree of variation. Two samples of MOS with different degree of polymerization (DP) and three samples of dextran with different molecular weight (MW) reported different fibrinolytic activity.

Covalent immobilization of Enterococcus faecalis Esawy dextransucrase and dextran synthesis

Enterococcus faecalis Esawy dextransucrase was immobilized in Fe(3+)-cross-linked alginate/carboxymethyl cellulose (AC) beads. The gel beads were modified with polyethylenimine (PEI) followed by glutaraldehyde (GA) to form Fe(3+) (ACPG) beads. Fe(3+) (ACPG) was characterized using FTIR and DSC techniques. GA activated beads showed new two peaks. The first was at 1,717 cm(-1) which refers to (CO) group of a free aldehyde end of glutaraldehyde, and another peak was at 1,660 cm(-1) referring to (CN) group. The immobilization process improved the optimum temperature from 35 to 45°C. The immobilized enzyme showed its optimum activity in wide pH range (4.5-5.4) compared to pH 5.4 in case of free form. Also, the immobilization process improved the thermal and pH enzyme stability to great extent. Reusability test proved that the enzyme activity retained 60% after 15 batch reactions. Immobilized enzyme was applied successfully in the synthesis of oligosaccharides and different molecular weights of dextran.