Cloning and characterization of a putative β-glucosidase (NfBGL595) from Neosartorya fischeri

Biochemical and in silico structural properties of a thermo-acid stable β-glucosidase from Beauveria bassiana

β-glucosidase hydrolyses the glycosidic bonds in cellobiose and cello-oligosaccharides, a critical step in the saccharification for biofuel production. Hence, the aim of this study was to gain insights into the biochemical and structural properties of a β-glucosidase from Beauveria bassiana, an entomopathogenic fungus. The β-glucosidase was purified to homogeneity using salt precipitation, ultrafiltration, and chromatographic techniques, attaining a specific activity of 496 U/mg. The molecular mass of the enzyme was then estimated via SDS-PAGE to be 116 kDa, while its activity pattern was confirmed by zymography using 4-methylumbelliferyl-β-d-glucopyranoside. Furthermore, the pH optima and temperature of the enzyme were found to be pH 5.0 and 60 °C respectively; its activity was significantly enhanced by Mg2+ and Na+ and was found to be relatively moderate in the presence of ethanol and dichloromethane. Molecular docking of the modelled B. bassiana β-glucosidase structure with the substrates, viz., 4-nitrophenyl β-d-glucopyranoside and cellobiose, revealed the binding affinity energies of -7.2 and -6.2 (kcal mol-1), respectively. Furthermore, the computational study predicted Lys-657, Asp-658, and Arg-1000 as the core amino acid residues in the catalytic site of the enzyme. This is the first investigation into a purified β-glucosidase from B. bassiana, providing valuable insights into the functional properties of carbohydrases from entomopathogenic fungal endophytes.

Homology analysis of 35 β-glucosidases in Oenococcus oeni and biochemical characterization of a novel β-glucosidase BGL0224

β-Glucosidases play an important role in food industry. Oenococcus oeni are typical lactic acid bacteria that initiate malolactic fermentation of wines. 35 β-glucosidases from O. oeni were selected and their conserved domains and evolutionary relationships were further explored in this study. The homology analysis results indicated that 35 β-glucosidases were basically derived from GH1 and GH3 family. A novel β-glucosidase was successfully expressed and characterized. The recombinant protein, referred to as BGL0224, consisted of a total 480 amino acids with an apparent molecular weight of 55.15 kDa and was classified as GH1 family. It achieved the highest activity at pH 5.0 and 50 °C. The activity and stability were significantly increased when 12% ethanol was supplemented to the enzyme. Using p-NPG as substrate, the K_m, V_max and K_cat of BGL0224 were 0.34 mM, 382.81 U/mg and 351.88 s^-1, respectively. In all, BGL0224 has good application prospects in food industry.

Glucose tolerant and glucose stimulated β-glucosidases - A review

The β-glucosidases (β-D-glucoside glucohydrolase, EC 3.2.1.21) hydrolyze glycosidic bonds of alkyl-, amino-, or aryl-β-D-glucosides, cyanogenic glucosides, disaccharides and short oligosaccharides and can also catalyze the synthesis of glycosyl-bonds between different molecules via transglycosylation. Due to their ubiquitous phylogenetic distribution, substrate diversity and ability to both hydrolyze and synthesize glycosidic bonds, the catalysis and regulation of β-glucosidases have been extensively studied. Many β-glucosidases are inhibited by the reaction product glucose, and reduced catalytic activity may limit the biotechnological and industrial applications of these enzymes and this has stimulated the search for β-glucosidases that maintain their activity at high glucose concentrations. Studies of many glucose tolerant enzymes have been reported and due to the ongoing interest in these enzymes, here it has been reviewed this accumulated body of knowledge which provides valuable insights as to the kinetics, structure, regulation and evolution of glucose tolerant and glucose stimulated β-glucosidases.

Purification and characterization of a novel GH1 beta-glucosidase from Jeotgalibacillus malaysiensis

Beta-glucosidase (BGL) is an important industrial enzyme for food, waste and biofuel processing. Jeotgalibacillus is an understudied halophilic genus, and no beta-glucosidase from this genus has been reported. A novel beta-glucosidase gene (1344 bp) from J. malaysiensis DSM 28777^T was cloned and expressed in E. coli. The recombinant protein, referred to as BglD5, consists of a total 447 amino acids. BglD5 purified using a Ni-NTA column has an apparent molecular mass of 52 kDa. It achieved the highest activity at pH 7 and 65 °C. The activity and stability were increased when CaCl₂ was supplemented to the enzyme. The enzyme efficiently hydrolyzed salicin and (1 → 4)-beta-glycosidic linkages such as in cellobiose, cellotriose, cellotetraose, cellopentose, and cellohexanose. Similar to many BGLs, BglD5 was not active towards polysaccharides such as Avicel, carboxymethyl cellulose, Sigmacell cellulose 101, alpha-cellulose and xylan. When BglD5 blended with Cellic® Ctec2, the total sugars saccharified from oil palm empty fruit bunches (OPEFB) was enhanced by 4.5%. Based on sequence signatures and tree analyses, BglD5 belongs to the Glycoside Hydrolase family 1. This enzyme is a novel beta-glucosidase attributable to its relatively low sequence similarity with currently known beta-glucosidases, where the closest characterized enzyme is the DT-Bgl from Anoxybacillus sp. DT3-1.

Catalytic properties, functional attributes and industrial applications of β-glucosidases

β-Glucosidases are diverse group of enzymes with great functional importance to biological systems. These are grouped in multiple glycoside hydrolase families based on their catalytic and sequence characteristics. Most studies carried out on β-glucosidases are focused on their industrial applications rather than their endogenous function in the target organisms. β-Glucosidases performed many functions in bacteria as they are components of large complexes called cellulosomes and are responsible for the hydrolysis of short chain oligosaccharides and cellobiose. In plants, β-glucosidases are involved in processes like formation of required intermediates for cell wall lignification, degradation of endosperm’s cell wall during germination and in plant defense against biotic stresses. Mammalian β-glucosidases are thought to play roles in metabolism of glycolipids and dietary glucosides, and signaling functions. These enzymes have diverse biotechnological applications in food, surfactant, biofuel, and agricultural industries. The search for novel and improved β-glucosidase is still continued to fulfills demand of an industrially suitable enzyme. In this review, a comprehensive overview on detailed functional roles of β-glucosidases in different organisms, their industrial applications, and recent cloning and expression studies with biochemical characterization of such enzymes is presented for the better understanding and efficient use of diverse β-glucosidases.

Role of the non-conserved amino acid asparagine 285 in the glycone-binding pocket of Neosartorya fischeri β-glucosidase

Neosartorya fischeriβ-glucosidase (NfBGL595) is distinguished from other BGLs by its high turnover forp-nitrophenyl β-d-glucopyranoside (pNPG) and flavones.

Characterization of a Mannose-6-Phosphate Isomerase from Bacillus amyloliquefaciens and Its Application in Fructose-6-Phosphate Production

The BaM6PI gene encoding a mannose-6-phosphate isomerase (M6PI, EC 5.3.1.8) was cloned from Bacillus amyloliquefaciens DSM7 and overexpressed in Escherichia coli. The enzyme activity of BaM6PI was optimal at pH and temperature of 7.5 and 70°C, respectively, with a k_cat/K_m of 13,900 s^-1 mM^-1 for mannose-6-phosphate (M6P). The purified BaM6PI demonstrated the highest catalytic efficiency of all characterized M6PIs. Although M6PIs have been characterized from several other sources, BaM6PI is distinguished from other M6PIs by its wide pH range and high catalytic efficiency for M6P. The binding orientation of the substrate M6P in the active site of BaM6PI shed light on the molecular basis of its unusually high activity. BaM6PI showed 97% substrate conversion from M6P to fructose-6-phosphate demonstrating the potential for using BaM6PI in industrial applications.

Fungal colonization and enzyme-mediated metabolism of waste coal by Neosartorya fischeri strain ECCN 84

Colonization and oxidative metabolism of South African low-rank discard coal by the fungal strain ECCN 84 previously isolated from a coal environment and identified as Neosartorya fischeri was investigated. Results show that waste coal supported fungal growth. Colonization of waste coal particles by N. fischeri ECCN 84 was associated with the formation of compact spherical pellets or sclerotia-like structures. Dissection of the pellets from liquid cultures revealed a nucleus of "engulfed" coal which when analyzed by energy dispersive X-ray spectroscopy showed a time-dependent decline in weight percentage of elemental carbon and an increase in elemental oxygen. Proliferation of peroxisomes in hyphae attached to coal particles and increased extracellular laccase activity occurred after addition of waste coal to cultures of N. fischeri ECCN 84. These results support a role for oxidative enzyme action in the biodegradation of coal and suggest that extracellular laccase is a key component in this process.

Biochemical properties of a novel glycoside hydrolase family 1 β-glucosidase (PtBglu1) from Paecilomyces thermophila expressed in Pichia pastoris

A novel β-glucosidase gene (PtBglu1) from the thermophilic fungus, Paecilomyces thermophila, was cloned and expressed in Pichia pastoris. PtBglu1 contained an open reading frame of 1440-bp nucleotides and encoded a protein of 479 amino acids which showed significant similarity to other fungal β-glucosidases from glycoside hydrolase (GH) family 1. The recombinant β-glucosidase (PtBglu1) was secreted at high level of 190.2 U mL(-1) in high cell density fermentor (5L). PtBglu1 was purified to homogeneity, and was found to be a glycoprotein with molecular mass of 56.7 kDa. The purified PtBglu1 showed optimum catalytic activity at pH 6.0 and 55 °C. The enzyme exhibited broad substrate specificity with highest activity toward pNP-β-D-glucopyranoside, followed by pNP-β-D-galactopyranoside and cellobiose. The K(m) values for pNP-β-D-glucopyranoside, cellobiose, gentiobiose and salicin were 0.55 mM, 1.0 mM, 1.74 mM and 6.85 mM, respectively. These properties make PtBglu1 a potential candidate for various industrial applications.

Flavour-active wine yeasts

The flavour of fermented beverages such as beer, cider, saké and wine owe much to the primary fermentation yeast used in their production, Saccharomyces cerevisiae. Where once the role of yeast in fermented beverage flavour was thought to be limited to a small number of volatile esters and higher alcohols, the discovery that wine yeast release highly potent sulfur compounds from non-volatile precursors found in grapes has driven researchers to look more closely at how choice of yeast can influence wine style. This review explores recent progress towards understanding the range of ‘flavour phenotypes’ that wine yeast exhibit, and how this knowledge has been used to develop novel flavour-active yeasts. In addition, emerging opportunities to augment these phenotypes by engineering yeast to produce so-called grape varietal compounds, such as monoterpenoids, will be discussed.