In Silico Phylogeny, Sequence and Structure Analyses of Fungal Thermoacidophilic GH11 Xylanases

Thermoacidophilic xylanase enzymes are mostly preferred for use as animal feed additives. In this study, we performed in silico phylogeny, sequence, structure, and enzyme-docked complex analyses of six thermoacidophilic GH11 xylanases belonging to various fungal species (Gymnopus androsaceus xylanase = GaXyl, Penicilliopsis zonata xylanase = PzXyl, Aspergillus neoniger xylanase = AnXyl, Calocera viscosa xylanase = CvXyl, Acidomyces richmondensis xylanase = ArXyl, Oidiodendron maius xylanase = OmXyl). To do this, amino acid sequences of six fungal thermoacidophilic GH11 xylanases, belonging to unreviewed protein entries in the UniProt/TrEMBL database, were investigated at molecular phylogeny and amino acid sequence levels. In addition, three-dimensional predicted enzyme models were built and then validated by using various bioinformatics programs computationally. The interactions between enzyme and the substrate were analyzed via docking program in the presence of two substrates (xylotetraose = X-4 and xylopentaose = X-5). According to molecular phylogeny analysis, three clusters of these enzymes occurred: the first group had PzXyl, AnXyl, and CvXyl, and the second group possessed GaXyl and OmXyl, and the third group included ArXyl. Multiple sequence alignment analysis demonstrated that the five xylanases (ArXyl, OmXyl, CvXyl, PzXyl, AnXyl) had longer N-terminal regions, indicating greater thermal stability, relative to the GaXyl. Homology modeling showed that all the predicted model structures were, to a great extent, conserved. Docking analysis results indicated that CvXyl, OmXyl, and AnXyl had higher binding efficiency to two substrates, compared to the GaXyl, PzXyl, and ArXyl xylanases, and CvXyl-X-4 docked complex had the highest substrate affinity with a binding energy of -9.8 kCal/mol. CvXyl, OmXyl, and AnXyl enzymes commonly had arginine in B8 beta- strand interacted with two substrates, different from the other enzymes having lower binding efficiency. As a result, it was concluded that the three thermoacidophilic xylanase enzymes might be better candidates as the animal feed additive

Identification and characterization of novel thermostable ?-amylase from Geobacillus sp. GS33

In this study, the heterologous expression and biochemical characterization of a thermostable ?-amylase from Geobacillus sp. GS33 was investigated. The recombinant ?-amylase was overexpressed in Escherichia coli BL21 (?DE) and purified via anion exchange and size-exclusion chromatography. The purified ?-amylase had a molecular weight of about 60 kDa, and was active in a broad range of pH 3–10 and temperature (40–90 °C) with maximum activity at pH 7–8 and 60 °C. The enzyme retained 50% residual activity at 65 °C, but only 20% at 85 °C after 16 h. At pH 9 and pH 7, the residual activity at 65 °C was 50% and 30%, respectively. The enzyme was remarkably activated by Co2+, Ca2+, Mg2+, PMSF, DTT, and Triton X-100, but partially inhibited by Cu2+, methanol, hexane, ethanol, acetone, SDS, and Tween 20. A molecular phylogeny analysis showed that the enzyme's amino acid sequence had the closest connection with an ?-amylase from Geobacillus thermoleovorans subsp. stromboliensis nov. 3D-structure-based amino acid sequence alignments revealed that the three catalytic residues (D217, E246, D314) and the four Ca2+ ion coordination residues (N143, E177, D186, H221) were conserved in ?-amylase from Geobacillus sp. GS33. The temperature stability and neutral pH optimum suggest that the enzyme may be useful for industrial applications. © 2020 Elsevier B.V.The authors would like to thank Biotechnology & Bioengineering Research Center at ?zmir Institute of Technology for the facilities and technical support

Comparative investigation of bacterial thermoalkaliphilic GH11 xylanases at molecular phylogeny, sequence and structure level

Thermoalkaliphilic GH11 xylanases are largely favored for paper pulp biobleaching process. The present work aimed to comparatively investigate the molecular phylogeny, amino acid sequences, molecular structure, and enzyme-substrate interaction of six thermoalkaliphilic GH11 xylanases from different bacterial species (Oxalobacteraceae bacterium xylanase = ObXyl, Sphingomonas sp. xylanase = SsXyl, Hymenobacter sp. xylanase = HsXyl, Amycolatopsis vastitatis xylanase = AvXyl, Lentzea deserti xylanase = LdXyl, Streptomyces rubellomurinus xylanase = SrXyl). For this purpose, six bacterial thermoalkaliphilic GH11 xylanase sequences derived from unreviewed protein entries of UniProt/TrEMBL database were analyzed for their phylogenetic relationships and sequence similarities. Also, 3D predicted structures of the enzymes were built and computationally validated by different bioinformatics tools. The enzyme-substrate interactions were investigated by molecular docking analysis using various substrates. Phylogenetic analysis showed that six enzymes were grouped into two different clusters: the first cluster included ObXyl, SsXyl, and HsXyl, whereas the second cluster had AvXyl, LdXyl, and SrXyl. Multiple sequence alignment showed that the second cluster xylanases possessed longer N-terminal regions indicating higher thermostability, compared to the first cluster xylanases. The structural analyses showed that six predicted structures were largely conserved. Molecular docking results indicated that binding efficiency to xylotriose, xylotetraose, and xylopentaose was higher in second cluster enzymes than that in first cluster enzymes, exhibiting mostly above -8.0 kCal/mol of binding energy. Arginine in B8 beta-strand was commonly involved in substrate interactions in all the second cluster xylanases, different from the first cluster ones. Thus, the present work predicted that the thermoalkaliphilic xylanases in the second cluster might be greater potential candidates for the paper pulp bleaching process

Structural and functional analyses of GH51 alpha-L-arabinofuranosidase of Geobacillus vulcani GS90 reveal crucial residues for catalytic activity and thermostability

Alpha-L-arabinofuranosidase (Abf) is of big interest in various industrial areas. Directed evolution is a powerful strategy to identify significant residues underlying Abf properties. Here, six active variants from GH51 Abf of Geobacillus vulcani GS90 (GvAbf) by directed evolution were overproduced, extracted, and analyzed at biochemical and structural levels. According to the activity and thermostability results, the most-active and the least-active variants were found as GvAbf51 and GvAbf52, respectively. GvAbf63 variant was more active than parent GvAbf by 20% and less active than GvAbf51. Also, the highest thermostability belonged to GvAbf52 with 80% residual activity after 1 h. Comparative sequence and structure analyses revealed that GvAbf51 possessed L307S displacement. Thus, this study suggested that L307 residue may be critical for GvAbf activity. GvAbf63 had H30D, Q90H, and L307S displacements, and H30 was covalently bound to E29 catalytic residue. Thus, H30D may decrease the positive effect of L307S on GvAbf63 activity, preventing E29 action. Besides, GvAbf52 possessed S215N, L307S, H473P, and G476C substitutions and S215 was close to E175 (acid–base residue). S215N may partially disrupt E175 action. Overall effect of all substitutions in GvAbf52 may result in the formation of the C–C bond between C171 and C213 by becoming closer to each other. © 2022 International Union of Biochemistry and Molecular Biology, Inc

Engineering of xylanases for the development of biotechnologically important characteristics

Xylanases are the main biocatalysts used for the reduction of the xylan backbone from hemicellulose, randomly splitting off beta-1,4-glycosidic linkages between xylopyranosyl residues. Xylanase market has been annually estimated at 500 million US Dollars and they are potentially used in broad industrial process ranges such as paper pulp biobleaching, xylo-oligosaccharide production, and biofuel manufacture from lignocellulose. The highly stable xylanases are preferred in the downstream procedure of industrial processes because they can tolerate severe conditions. Almost all native xylanases can not endure adverse conditions thus they are industrially not proper to be utilized. Protein engineering is a powerful technology for developing xylanases, which can effectively work in adverse conditions and can meet requirements for industrial processes. This study considered state-of-the-art strategies of protein engineering for creating the xylanase gene diversity, high-throughput screening systems toward upgraded traits of the xylanases, and the prediction and comprehensive analysis of the target mutations in xylanases by in silico methods. Also, key molecular factors have been elucidated for industrial characteristics (alkaliphilic enhancement, thermal stability, and catalytic performance) of GH11 family xylanases. The present review explores industrial characteristics improved by directed evolution, rational design, and semi-rational design as protein engineering approaches for pulp bleaching process, xylooligosaccharides production, and biorefinery & bioenergy production

A novel thermostable xylanase from Geobacillus vulcani GS90: Production, biochemical characterization, and its comparative application in fruit juice enrichment

Xylanases have great attention to act as a potential role in agro-industrial processes. In this study, production, characterization, and fruit juice application of novel xylanase from thermophilic Geobacillus vulcani GS90 (GvXyl) were performed. GvXyl was purified via acetone precipitation and gel-filtration chromatography. The results showed that GvXyl had 1,671.4 U/mg of specific activity and optimally worked at pH 8 and 55°C. It was also active in a wide pH (3–9) and temperature (30–90ºC) ranges. GvXyl was highly stable at 90ºC and relatively stable at pH 3–9. The kinetic parameters of GvXyl were obtained as Km, Vmax, and kcat; 10.2 mg/ml, 4,104 µmol min?1 mg?1, and 3,542.6 s?1, respectively. GvXyl had higher action than commercial xylanase in fruit juice enrichment. These results revealed that GvXyl might possess a potential influence in fruit juice processing because of its high specific activity and great thermal stability. Practical applications: Polysaccharides include starch, pectin, and hemicellulose create problems by lowering fruit juice quality in beverages. To overcome this problem, various clarification processes might be applied to natural fruit juices. Even though chemicals are widely used for this purpose, recently enzymes including xylanases are preferred for obtaining high-quality products. In this study, we reported the production and biochemical characterization of novel thermostable xylanase from thermophilic G. vulcani GS90 (GvXyl). Also, apple and orange juice enrichment were performed with the novel xylanase to increase the quality in terms of yield, clarity, and reducing sugar substance. The improved quality features of apple and orange juices with GvXyl was then compared to commercially available ?-1,4-xylanase. The results revealed that GvXyl might possess a potential influence in fruit juice processing because of its high specific activity and great thermal stability. © 2021 Wiley Periodicals LLC.The authors thank Biotechnology & Bioengineering Research Center at ?zmir Institute of Technology for the facilities and technical support

Thermoalkalophilic recombinant esterase entrapment in chitosan/calcium/alginate-blended beads and its characterization

BACKGROUND: Esterases (EC 3.1.1.1), a class of hydrolases, degrade the ester bonds of lipids into alcohol and carboxylic acids and synthesize carboxylic ester bonds. They are used in a variety of biotechnological, industrial, environmental, and pharmaceutical applications due to their many valuable properties. Particularly, extremophilic esterases with many superior properties are of great interest for various reactions. Immobilization of enzymes may provide some advantages over free enzymes not only to improve the properties of enzymes but also to increase the reusability of biocatalyst in industrial applications. Therefore, many different immobilization applications for enzymes have been reported in various studies. To our knowledge, a thermophilic esterase has not so far been immobilized by entrapment using chitosan/calcium/alginate-blended beads. Here, we reported the immobilization of thermoalkalophilic recombinant esterase by entrapment using chitosan/calcium/alginate-blended beads, and then the entrapped esterase was characterized biochemically in details. RESULTS: In the present study, a thermophilic recombinant esterase was immobilized by entrapment in chitosan/calcium/alginate-blended beads for the first time. The 0.5 mg mL?1 purified recombinant esterase was entrapped in 1% chitosan, 2% alginate, and 0.7 M CaCl2 blended beads. The results showed that immobilization yield and entrapment efficiency of the entrapped esterase were 69.5% and 80.4%, respectively. SEM micrograph showed that the surface of the beads resembled a mesh and very compact structures. Chitosan/calcium/alginate-blended beads exhibited an 18.8% swelling ratio and had a moderate porous structure. The entrapment technique highly enhanced the thermostability of the esterase and shifted its optimum temperature from 65 to 80 °C. The immobilized esterase was very stable in a wide range of pH (8.5–11) displaying maximum activity at pH 9. ZnCl2 slightly increased the activity of immobilized esterase whereas several metal ions reduced the enzyme activity. When the enzyme was immobilized in chitosan/calcium/alginate-blended beads, its Km increased about 2 times and Vmax value decreased almost 1.5 times. Immobilization allowed repeated uses of the esterase having good operational stability in a continuous process. CONCLUSION: The results revealed that the immobilization of a thermophilic recombinant esterase by entrapment in chitosan/calcium/alginate-blended beads exhibited considerably better compared to other immobilization processes with various entrapment strategies. © 2021 Society of Chemical Industry (SCI). © 2021 Society of Chemical Industry (SCI).The authors would like to thank Biotechnology & Bioengineering Research Center at ?zmir Institute of Technology for the facilities and technical support

Purification and Biochemical Characterization of a Novel Thermostable Serine Protease from Geobacillus sp. GS53

Proteases account for approximately 60% of the enzyme market in the world, and they are used in various industrial applications including the detergent industry. In this study, production and characterization of a novel serine protease of thermophilic Geobacillus sp. GS53 from Balçova geothermal region, İzmir, Turkey, were performed. The thermostable protease was purified through ammonium sulfate precipitation and anion-exchange chromatography. The results showed that the protease had 137.8 U mg?1 of specific activity and optimally worked at 55 oC and pH 8. It was also active in a broad pH (4–10) and temperature (25–75 °C) ranges. The protease was highly stable at 85 °C and demonstrated relative stability at pH 4, 7, and 10. Also, the enzyme had high stability against organic solvents and surfactants; enzyme relative activity did not decrease below 81% upon preincubation for 10 min. Ca2+, Cu2+, and Zn2+ ions slightly induced protease activity. The protease was highly specific to casein, skim milk, Hammerstein casein, and BSA substrates. These results revealed that the protease might have a potential effect in a variety of industrial fields, especially the detergent industry, because of its high thermostability and stability to surfactants. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.The authors would like to thank Biotechnology & Bioengineering Research Center at ?zmir Institute of Technology for the facilities and technical support

A thermophilic α-l-Arabinofuranosidase from Geobacillus vulcani GS90: heterologous expression, biochemical characterization, and its synergistic action in fruit juice enrichment

α-l-Arabinofuranosidases with an orchestral action of xylanolytic enzymes degrades the xylan in plant cell wall. In this study, heterologous expression, biochemical characterization, and synergistic action of α-l-Arabinofuranosidase from previously identified.Geobacillus vulcani GS90 (GvAbf) was investigated. The recombinant α-l-Arabinofuranosidase was overexpressed in Escherichia coli BL21 (λDE) and purified via His-tag Ni-affinity and size-exclusion chromatography. Optimum activity of the purified α-l-Arabinofuranosidase was obtained at pH 5 and at 70 °C. The GvAbf was active in a broad pH and temperature ranges; pH 4–9 and 30–90 °C, respectively. In addition, it retained most of its activity after an hour incubation at 70 °C and remained relatively stable at pH 3–6. GvAbf was quite stable against various metal ions. The kinetic parameters of GvAbf was obtained as Vmax and Km; 200 U/mg and 0.2 mM with p-nitrophenyl-α-l-arabinofuranoside and 526 U/mg and 0.1 mM with sugar beet arabinan, respectively. The synergistic action of GvAbf was studied with commercially available xylanase on juice enrichment of apples, grapes, oranges, and peaches. The best juice enrichment in terms of clarity, reducing sugar content, and yield, was achieved with GvAbf and xylanase together compared to treatment with xylanase and GvAbf alone in all fruits. The treatment with GvAbf and xylanase together lead to an increased juice yield by 26.56% (apple), 30.88% (grape), 40.00% (orange) and 32.20% (peach) as well as having a significant effect on juice clarity by an increase of % transmittance 47.26, 25.98, 41.77, and 44.97, respectively. The highest reducing sugar level of fruit juices also obtained with GvAbf and xylanase together compared to treatment with xylanase and GvAbf alone in all types of fruits. GvAbf and xylanase together as simultaneous synergistic manner may have an exciting potential for application in fruit juice processing