Characterization of novel lignocellulose-degrading enzymes from the porcupine microbiome using synthetic metagenomics

Plant cell walls are composed of cellulose, hemicellulose, and lignin, collectively known as lignocellulose. Microorganisms degrade lignocellulose to liberate sugars to meet metabolic demands. Using a metagenomic sequencing approach, we previously demonstrated that the microbiome of the North American porcupine (Erethizon dorsatum) is replete with genes that could encode lignocellulose-degrading enzymes. Here, we report the identification, synthesis and partial characterization of four novel genes from the porcupine microbiome encoding putative lignocellulose-degrading enzymes: β-glucosidase, α-L-arabinofuranosidase, β-xylosidase, and endo-1,4-β-xylanase. These genes were identified via conserved catalytic domains associated with cellulose- and hemicellulose-degradation. Phylogenetic trees were created for each of these putative enzymes to depict genetic relatedness to known enzymes. Candidate genes were synthesized and cloned into plasmid expression vectors for inducible protein expression and secretion. The putative β-glucosidase fusion protein was efficiently secreted but did not permit Escherichia coli (E. coli) to use cellobiose as a sole carbon source, nor did the affinity purified enzyme cleave p-Nitrophenyl β-D-glucopyranoside (p-NPG) substrate in vitro over a range of physiological pH levels (pH 5–7). The putative hemicellulose-degrading β-xylosidase and α-L-arabinofuranosidase enzymes also lacked in vitro enzyme activity, but the affinity purified endo-1,4-β-xylanase protein cleaved a 6-chloro-4-methylumbelliferyl xylobioside substrate in acidic and neutral conditions, with maximal activity at pH 7. At this optimal pH, K_M, V_max, and k_cat were determined to be 32.005 ± 4.72 μM, 1.16x10^-5 ± 3.55x10^-7 M/s, and 94.72 s^-1, respectively. Thus, our pipeline enabled successful identification and characterization of a novel hemicellulose-degrading enzyme from the porcupine microbiome. Progress towards the goal of introducing a complete lignocellulose-degradation pathway into E. coli will be accelerated by combining synthetic metagenomic approaches with functional metagenomic library screening, which can identify novel enzymes unrelated to those found in available databases.

The insecticidal activity of Satureja hortensis essential oil and its active ingredient -carvacrol against Acrobasis advenella (Zinck.) (Lepidoptera, Pyralidae)

Nowadays, Acrobasis advenella is considered a pest of the highest economic significance in black chokeberry plantations, negatively affecting the quantity and quality of fruits. The aim of this study was to investigate the effect of Satureja hortensis essential oil and its main constituent, carvacrol, on the life cycle and physiology of A. advenella. The metabolic activity of both preparations was evaluated against insect α- and β- glucosidase, catalase, peroxidase and polyphenol oxidase. The results showed S. hortensis essential oil and carvacrol, are characterized by insecticidal activity against A. advenella larvae. It found an increase in catalase activity in A. advenella homogenates under the influence of carvacrol and an induction of polyphenol oxidase by S. hortensis EO with no changes in POX activity. Also, it was shown that the activity of α- and β-glucosidase significantly increased in larvae fed on inflorescences treated with the essential oil and carvacrol. These preparations particularly strongly affected β-glucosidase activity in the insect homogenates. S. hortensis essential oil reduced emergence the longevity of moths. The obtained results suggest that S. hortensis essential oil and carvacrol can be useful in protecting organic crops of black chokeberry but essential oils may be more effective biopesticides than their active ingredients separately.

The Legacy Effects of Winter Climate on Microbial Functioning After Snowmelt in a Subarctic Tundra

Warming-induced increases in microbial CO₂ release in northern tundra may positively feedback to climate change. However, shifts in microbial extracellular enzyme activities (EEAs) may alter the impacts of warming over the longer term. We investigated the in situ effects of 3 years of winter warming in combination with the in vitro effects of a rapid warming (6 days) on microbial CO₂ release and EEAs in a subarctic tundra heath after snowmelt in spring. Winter warming did not change microbial CO₂ release at ambient (10 °C) or at rapidly increased temperatures, i.e., a warm spell (18 °C) but induced changes (P < 0.1) in the Q₁₀ of microbial respiration and an oxidative EEA. Thus, although warmer winters may induce legacy effects in microbial temperature acclimation, we found no evidence for changes in potential carbon mineralization after spring thaw.

Defense responses of Thuja orientalis to infestation of anholocyclic species aphid Cinara tujafilina

The aim of this study was to determine an interdependence between generation of semiquinone radicals, superoxide anion (O₂-), manganese ions (Mn²⁺) and phenolic content in leaves of Thuja orientalis in response to infestation by varying populations of Cinara tujafilina, i.e. 40 or 80 aphids per plant. Also, superoxide dismutase (SOD) and β-d-glucosidase activities in leaves of T. orientalis in a defense response to C. tujafilina was recorded. Analyses of electron paramagnetic resonance (EPR) showed generally a higher concentration of semiquinone radicals with g-values of 2.0051 ± 0.0005 and 20032 ± 0.0005 after C. tujafilina infestation in leaves in comparison to the control. Up to 48 h post-infestation in leaves infested by 80 aphids the level of semiquinone radicals was significantly higher than in the control, while in leaves infested by 40 aphids the highest concentrations of these radicals were recorded at later time points (i.e. at 72 and 96 hpi). In parallel, the highest total generation of O₂- and low activity of SOD were recorded in 24-h leaves infested by 80 aphids. Additionally, analysis of confocal images showed that the strongest yellow fluorescence indicating O₂- generation was detected in epidermal cells of leaves up to 48 hpi. Significant reduction of Mn²⁺ ions detected by EPR spectroscopy in relation to the control was observed in 4-w leaves infested by 80 and 40 aphids and in 48-h leaves infested by 40 aphids. Phenolic contents in leaves infested by 80 and 40 aphids at all time points were higher than in the control. The greatest β-d-glucosidase activity and phenolic contents were recorded at 96 h of feeding. These results indicate that the perception of C. tujafilina infestation by T. orientalis leaves induces a specified sequence of defense mechanisms in the course of time.

Enhancing the Thermostability of Highly Active and Glucose-Tolerant β-Glucosidase Ks5A7 by Directed Evolution for Good Performance of Three Properties

A high-performance β-glucosidase for efficient cellulose hydrolysis needs to excel in thermostability, catalytic efficiency, and resistance to glucose inhibition. However, it is challenging to achieve superb properties in all three aspects in a single enzyme. In this study, a hyperactive and glucose-tolerant β-glucosidase Ks5A7 was employed as the starting point. Four rounds of random mutagenesis were then performed, giving rise to a thermostable mutant 4R1 with five amino acid substitutions. The half-life of 4R1 at 50 °C is 8640-fold that of Ks5A7 (144 h vs 1 min). Meanwhile, 4R1 had a higher specific activity (374.26 vs 243.18 units·mg^-1) than the wild type with a similar glucose tolerance. When supplemented to Celluclast 1.5L, the mutant significantly enhanced the hydrolysis of pretreated sugar cane bagasse, improving the released glucose concentration by 44%. With excellent performance in thermostability, activity, and glucose tolerance, 4R1 will serve as an exceptional catalyst for industrial applications.

Soybean ultrasound pre-treatment prior to soaking affects β-glucosidase activity, isoflavone profile and soaking time

Ultrasound may convert conjugated isoflavones into their corresponding aglycones, the best form for absorption in the human body. However, ultrasound may also influence the activity of endogenous β-glucosidase. Therefore, the present work evaluated the effects of soybean ultrasound pre-treatment by applying the Box-Behnken design prior to soaking, a step that is important for industries to prepare certain soy products. Furthermore, a multi-response optimisation is provided. The best conditions for soybean ultrasound pre-treatment were established as temperature, X1 = 55 °C; exposure time, X2 = 5 min and ultrasound intensity, X3 = 19.5 W cm-2. Under these conditions, soybeans with higher contents of aglycones were obtained and β-glucosidase activity was kept as high as possible. A second experiment was conducted and confirmed that ultrasound pre-treatment results in a lower soaking time (2 h) to achieve the highest moisture content, lower hardness as well as increased content of aglycones.

Multi-substrate induced microbial respiration, nitrification potential and enzyme activities in metal-polluted, EDTA-washed soils

Efficiency and the preservation of soil functions are key requirements for sustainable remediation of contaminated soil. Microbial decomposition and conversion of substrates is a fundamental soil function. Pilot-scale EDTA-based soil washing recycled chelant generated no wastewater and removed 78% of Pb from acidic farmland soil with 860 mg kg^-1 Pb and 60% of Pb from calcareous garden soil with 1030 mg kg^-1 Pb. Remediation had an insignificant effect on microbial respiration in acidic soil induced by sequential additions of glucose, micro-cellulose, starch and alfa-alfa sprout powder (mimicking litter components, C-cycle). In contrast, remediation of calcareous soil reduced cumulative CO₂ production after glucose (simple) and alfalfa (complex substrate) addition, by up to 40%. Remediation reduced the nitrification rate (denoting the N-cycle) in acidic soil by 30% and halved nitrification in calcareous soil. Remediation in both soils slightly or positively affected dehydrogenase and β-glucosidase activity (associated with C-cycle), and decreased urease activity (N-cycle). Generally, EDTA remediation modestly interfered with substrate utilisation in acidic soil. A more prominent effect of remediation on the functioning of calcareous soil could largely be attributed to the use of a higher EDTA dose (30 vs. 100 mmol kg^-1, respectively).

Untargeted metabolite profiling for koji-fermentative bioprocess unravels the effects of varying substrate types and microbial inocula

Untargeted metabolomics unraveled the effects of varying substrates (soybean, wheat, and rice) and inocula (Aspergillus oryzae and Bacillus amyloliquefaciens) on metabolite compositions of koji, a starter ingredient in various Asian fermented foods. Multivariate analyses of the hyphenated mass spectrometry datasets for different koji extracts highlighted 61 significantly discriminant primary metabolites (sugars and sugar alcohols, organic acids, amino acids, fatty acids, nucleosides, phenolic acids, and vitamins) according to varying substrates and inocula combinations. However, 59 significantly discriminant secondary metabolites were evident for koji-types with varying substrates only, viz., soybean (flavonoids, soyasaponins, and lysophospholipids), wheat (flavones and lysophospholipids), and rice (flavonoids, fatty acids derivatives, and lysophospholipids). Independently, the substrates influenced primary metabolite compositions in koji (soybean > wheat, rice). The inocula choice of A. oryzae engendered higher carbohydrates, organic acids, and lipid derivative levels commensurate with high α-amylase and β-glucosidase activities, while B. amyloliquefaciens affected higher amino acids levels, in respective koji types.

Improved cellulosic ethanol production from corn stover with a low cellulase input using a β-glucosidase-producing yeast following a dry biorefining process

A low-cost and sustainable cellulosic ethanol production is vital for fermentation-based industrial applications. Reducing the expenses of cellulose-deconstruction enzymes is one of the significant challenges to economic cellulose-to-ethanol conversion. Here, we report the improved ethanol production from corn stover after dry biorefining using a natural β-glucosidase-producing strain Clavispora NRRL Y-50464 with a low cellulase dose of 5 mg protein/g glucan under separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) conditions. Strain Clavispora NRRL Y-50464 exhibited a superior ethanol fermentation performance over Saccharomyces cerevisiae DQ1 under both conditions. It produced an ethanol titer of 38.1 g/L within 96 h at a conversion efficiency of 55.5% with 25% solids loading (w/w) via SSF without addition of extra β-glucosidase supplement. Improved performance of Y-50464 on a bioreactor with a helical stirring apparatus confirmed its advantage over the conventional bioreactors originally designed for liquid fermentations in cellulosic ethanol conversion by SSF. The results of this study suggested that the strain Clavispora NRRL Y-50464 has a potential as a candidate for lower-cost cellulosic ethanol production from lignocellulosic materials.

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.

Biochemical Characterization of the GBA2 c.1780G>C Missense Mutation in Lymphoblastoid Cells from Patients with Spastic Ataxia

The GBA2 gene encodes the non-lysosomal glucosylceramidase (NLGase), an enzyme that catalyzes the conversion of glucosylceramide (GlcCer) to ceramide and glucose. Mutations in GBA2 have been associated with the development of neurological disorders such as autosomal recessive cerebellar ataxia, hereditary spastic paraplegia, and Marinesco-Sjogren-Like Syndrome. Our group has previously identified the GBA2 c.1780G>C [p.Asp594His] missense mutation, in a Cypriot consanguineous family with spastic ataxia. In this study, we carried out a biochemical characterization of lymphoblastoid cell lines (LCLs) derived from three patients of this family. We found that the mutation strongly reduce NLGase activity both intracellularly and at the plasma membrane level. Additionally, we observed a two-fold increase of GlcCer content in LCLs derived from patients compared to controls, with the C₁₆ lipid being the most abundant GlcCer species. Moreover, we showed that there is an apparent compensatory effect between NLGase and the lysosomal glucosylceramidase (GCase), since we found that the activity of GCase was three-fold higher in LCLs derived from patients compared to controls. We conclude that the c.1780G>C mutation results in NLGase loss of function with abolishment of the enzymatic activity and accumulation of GlcCer accompanied by a compensatory increase in GCase.

Biotransformation of soy flour isoflavones by Aspergillus niger NRRL 3122 β-glucosidase enzyme

β-glucosidase enzyme produced from Aspergillus niger NRRL 3122 has been partially purified and characterised. Its molecular weight was 180 KDa. The optimal pH and temperature were 3.98 and 55 °C, respectively. It promoted the hydrolysis of soy flour isoflavone glycosides to their aglycone. Two-level Plackett-Burman design was applied and effective variables for genistein production were determined. Reaction time had a significant positive effect, and pH had a significant negative effect. They were further evaluated using Box-Behnken model. Accordingly, the optimal combination of the major reaction affecting factors was reaction time, 5 h and pH, 4. The concentration of genistein increased by 11.73 folds using this optimal combination. The antioxidant activity of the non-biotransformed and biotransformed soy flour extracts was determined by DPPH method. It was found that biotransformation increased the antioxidant activity by four folds.

Biochemical and microbiological activity of soil contaminated with o-cresol and biostimulated with Perna canaliculus mussel meal

The choice of the study subject was a consequence of the growing interest in volatile organic compounds which are strongly dispersed in the environment. The knowledge of o-cresol's capability for being broken down by bacteria should be supplemented by studies aimed at determining the biochemical and microbiological activity of soils. o-Cresol was applied at the following rates: 0, 0.1, 1, 10, and 50 mg of o-cresol kg^-1 d.m. of soil to determine its effect on the biological properties of soil. The activity of dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and β-glucosidase, the eight groups of microorganism counts, was determined in soil samples after 45 days and the barley yield was determined. Preventive biostimulation with Perna canaliculus mussel meal, illustrated by means of the index of fertility (IF), was conducted in order to eliminate the adverse effect of o-cresol. The soil and crop resistance index (RS) was used to illustrate the response of barley, and R:S-the rhizosphere effect index was used to determine the effect of the crop on the enzymatic activity of soil. o-Cresol had a beneficial effect on the biological activity of soil at an acceptable rate of 0.1 and 1 mg kg^-1 d.m. of soil, and it became its inhibitor after being applied at 10 and 50 mg kg^-1 d.m. of soil, which also brought about a decrease in the resistance of spring barley. Dehydrogenases are the most sensitive, and catalase is the least sensitive, to the pressure of o-cresol in soil. Mussel meal can be recommended as a biostimulator of soil fertility. It also eliminated the negative effect of o-cresol on its biological activity.

Linkages between straw decomposition rate and the change in microbial fractions and extracellular enzyme activities in soils under different long-term fertilization treatments

In order to study the linkages between straw decomposition rate and the change in soil biological properties after straw addition to different fertilized soils, we collected soils from three long-term fertilization treatments (no-fertilizer, CK; nitrogen, phosphorus, and potassium fertilizers, NPK; NPK plus straw (S), NPKS), and incubated maize straw with these soils at 25°C for 75 days. The average straw carbon dioxide (CO2) emission rate in the CK+straw (S), NPK+S, and NPKS+S treatments was 0.58±0.51, 0.66±0.53, and 0.74±0.58 μg C g-1soil h-1, respectively. The average increase in the contents of fungi, bacteria, and Actinomycetes under straw addition treatments than the control soils (CK, NPK, and NPKS, respectively) changed in the order of CK+S≤NPK+S <NPKS+S, while bacteria and Actinomycetes peaked later in the CK+SthanNPK+S and NPKS+S treatments. Bacterial abundance unchanged, Actinomycetes abundance decreased, but fungal abundance significantly increased in soils after straw addition. The average increase in the activities of β-glucosidase (BG), β-D-cellobiosidase (CB), and β-xylosidase (XYL) differed as: CK+S<NPK+S ≤ NPKS+S, and the highest activities and increments of them occurred later in the CK+S than NPK+S and NPKS+S treatments. Straw CO2 emission rate was poorly correlated with changes in the contents of microbial fractions across all straw addition treatments, but it was significant positively correlated with the increased activities of BG, CB, and XYL under the NPK+S and NPKS+S treatments. Our results indicated that chemical fertilization and straw return soils differently increased straw decomposition because of the different increases in microbial fractions and soil enzyme activities when compared to the no-fertilizer soil, and the decomposition process was more closely correlated with C-obtaining enzymes than microbial fractions.

Biocatalysis of Platycoside E and Platycodin D3 Using Fungal Extracellular β-Glucosidase Responsible for Rapid Platycodin D Production

Platycodi radix (i.e., Platycodon grandiflorum root) products (e.g., tea, cosmetics, and herbal supplements) are popular in East Asian nutraceutical markets due to their reported health benefits and positive consumer perceptions. Platycosides are the key drivers of Platycodi radixes' biofunctional effects; their nutraceutical and pharmaceutical activities are primarily related to the number and varieties of sugar side-chains. Among the various platycosides, platycodin D is a major saponin that demonstrates various nutraceutical activities. Therefore, the development of a novel technology to increase the total platycodin D content in Platycodi radix extract is important, not only for consumers' health benefits but also producers' commercial applications and manufacturing cost reduction. It has been reported that hydrolysis of platycoside sugar moieties significantly modifies the compound's biofunctionality. Platycodi radix extract naturally contains two major platycodin D precursors (platycoside E and platycodin D3) which can be enzymatically converted to platycodin D via β-d-glucosidase hydrolysis. Despite evidence that platycodin D precursors can be changed to platycodin D in the Platycodi radix plant, there is little research on increasing platycodin D concentrations during processing. In this work, platycodin D levels in Platycodi radix extracts were significantly increased via extracellular Aspergillus usamii β-d-glucosidase (n = 3, p < 0.001). To increase the extracellular β-d-glucosidase activity, A. usamii was cultivated in a culture media containing cellobiose as its major carbon source. The optimal pH and temperature of the fungal β-d-glucosidase were 6.0 and 40.0 °C, respectively. Extracellular A. usamii β-d-glucosidase successfully converted more than 99.9% (w/v, n = 3, p < 0.001) of platycoside E and platycodin D3 into platycodin D within 2 h under optimal conditions. The maximum level of platycodin D was 0.4 mM. Following the biotransformation process, the platycodin D was recovered using preparatory High Performance Liquid Chromatography (HPLC) and applied to in vitro assays to evaluate its quality. Platycodin D separated from the Platycodi radix immediately following the bioconversion process showed significant anti-inflammatory effects from the Lipopolysaccharide (LPS)-induced macrophage inflammatory responses with decreased nitrite and IL-6 production (n = 3, p < 0.001). Taken together, these results provide evidence that biocatalysis of Platycodi radix extracts with A. usamii may be used as an efficient method of platycodin D-enriched extract production and novel Platycodi radix products may thereby be created.

Revealing Clusters of Connected Pathways Through Multisource Data Integration in Huntington's Disease and Spastic Ataxia

The advancement of scientific and medical research over the past years has generated a wealth of experimental data from multiple technologies, including genomics, transcriptomics, proteomics, and other forms of -omics data, which are available for a number of diseases. The integration of such multisource data is a key component toward the success of precision medicine. In this paper, we are investigating a multisource data integration method developed by our group, regarding its ability to drive to clusters of connected pathways under two different approaches: first, a disease-centric approach, where we integrate data around a disease, and second, a gene-centric approach, where we integrate data around a gene. We have used as a paradigm for the first approach Huntington's disease (HD), a disease with a plethora of available data, whereas for the second approach the GBA2, a gene that is related to spastic ataxia (SA), a phenotype with sparse availability of data. Our paper shows that valuable information at the level of disease-related pathway clusters can be obtained for both HD and SA. New pathways that classical pathway analysis methods were unable to reveal, emerged as necessary "connectors" to build connected pathway stories formed as pathway clusters. The capability to integrate multisource molecular data, concluding to something more than the sum of the existing information, empowers precision and personalized medicine approaches.

Simultaneous Observation of the Orientation and Activity of Surface-Immobilized Enzymes

Surface immobilized enzymes have been widely used in many applications such as biosensors, biochips, biofuel production, and biofuel cell construction. Many factors dictate how enzymes' structure, activity, and stability may change when immobilized, including surface functionalization, immobilization chemistry, nature of the solid support, and enzyme surface density. To better understand how immobilization affects enzyme structure and activity, we have developed a method to measure both surface-sensitive protein vibrational spectra and enzymatic activity simultaneously. To accomplish this, an optical/fluorescence microscope was incorporated into a sum frequency generation (SFG) spectrometer. Using β-glucosidase (β-Glu) as a model system, enzymes were covalently tethered to a self-assembled monolayer surface using cysteine-maleimide chemistry. Their orientations were determined by SFG spectroscopy, with a single native cysteine residue oriented toward the functionalized surface, and activity measured simultaneously using a fluorogenic substrate resorufin β-d-glucopyranoside, with a loss of activity of 53% as compared to comparable solution measurements. Measuring β-Glu activity and orientation simultaneously provides more accurate information for designing and further improving enzymatic activity of surface-bound enzymes.

Repeated disturbances affect functional but not compositional resistance and resilience in an aquatic bacterioplankton community

Disturbances are believed to be one of the main factors influencing variations in community diversity and functioning. Here we investigated if exposure to a pH press disturbance affected the composition and functional performance of a bacterial community and its resistance, recovery and resilience to a second press disturbance (salt addition). Lake bacterial assemblages were initially exposed to reduced pH in six mesocosms whereas another six mesocosms were kept as reference. Seven days after the pH disturbance, three tanks from each treatment were exposed to a salt disturbance. Both bacterial production and enzyme activity were negatively affected by the salt treatment, regardless if the communities had been subject to a previous disturbance or not. However, cell-specific enzyme activity had a higher resistance in communities pre-exposed to the pH disturbance compared to the reference treatment. In contrast, for cell-specific bacterial production resistance was not affected, but recovery was faster in the communities that had previously been exposed to the pH disturbance. Over time, bacterial community composition diverged among treatments, in response to both pH and salinity. The difference in functional recovery, resilience and resistance may depend on differences in community composition caused by the pH disturbance, niche breadth or acquired stress resistance.

Reveal the response of enzyme activities to heavy metals through in situ zymography

Enzymes in the soil are vital for assessing heavy metal soil pollution. Although the presence of heavy metals is thought to change the soil enzyme system, the distribution of enzyme activities in heavy metal polluted-soil is still unknown. For the first time, using soil zymography, we analyzed the distribution of enzyme activities of alfalfa rhizosphere and soil surface in the metal-contaminated soil. The results showed that the growth of alfalfa was significantly inhibited, and an impact that was most pronounced in seedling biomass and chlorophyll content. Catalase activity (CAT) in alfalfa decreased with increasing heavy metal concentrations, while malondialdehyde (MDA) content continually increased. The distribution of enzyme activities showed that both phosphatase and β-glucosidase activities were associated with the roots and were rarely distributed throughout the soil. In addition, the total hotspot areas of enzyme activities were the highest in extremely heavy pollution soil. The hotspot areas of phosphatase were 3.4%, 1.5% and 7.1% under none, moderate and extremely heavy pollution treatment, respectively, but increased from 0.1% to 0.9% for β-glucosidase with the increasing pollution levels. Compared with the traditional method of enzyme activities, zymography can directly and accurately reflect the distribution and extent of enzyme activity in heavy metals polluted soil. The results provide an efficient research method for exploring the interaction between enzyme activities and plant rhizosphere.

Bio-pesticidal effects of Trichoderma viride formulated titanium dioxide nanoparticle and their physiological and biochemical changes on Helicoverpa armigera (Hub.)

The control of agricultural pests through eco-friendly nanopesticides is a challenge of crucial environmental importance nowadays. The current study was aimed to discover a novel biopesticides through Trichoderma viride mediated synthesis of titanium dioxide nanoparticles (TDNPs). The main chemical and physical features of the TDNPs were assessed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and size distribution and shape of the NPs studied through the scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM) and dynamic light scattering (DLS). The extracellular synthesized nanoparticles were evaluated for their larvicidal, antifeedant and pupicidal activities against Helicoverpa armigera. TDNPs exhibited highest mortality rate on first (100%), second (100%) and third (92.34%), instar larvae of H. armigera at 100 ppm. The detoxifying enzymes such as, β-glucosidase and carboxylesterase were reduced whereas glutathione S-transferase increased during the treatment of TDNPs against H. armigera at 100 ppm. No toxic effects were found on Eudrilus eugeniae filter paper and artificial soil assays treated with TDNPs at 100 ppm. However, cypermethrin was toxic to earthworms after 72 h treatment. Therefore, TDNPs could act as significant inhibitors on the development of H. armigera, although, no adverse effect was found on earthworms.

A highly glucose-tolerant GH1 β-glucosidase with greater conversion rate of soybean isoflavones in monogastric animals

In the feed industry, β-glucosidase has been widely used in the conversion of inactive and bounded soybean isoflavones into active aglycones. However, the conversion is frequently inhibited by the high concentration of intestinal glucose in monogastric animals. In this study, a GH1 β-glucosidase (AsBG1) with high specific activity, thermostability and glucose tolerance (IC50 = 800 mM) was identified. It showed great glucose tolerance against substrates with hydrophobic aryl ligands (such as pNPG and soy isoflavones). Using soybean meal as the substrate, AsBG1 exhibited higher hydrolysis efficiency than the GH3 counterpart Bgl3A with or without the presence of glucose in the reaction system. Furthermore, it is the first time to find that the endogenous β-glucosidase of soybean meal, mostly belonging to GH3, plays a role in the hydrolysis of soybean isoflavones and is highly sensitive to glucose. These findings lead to a conclusion that the GH1 rather than GH3 β-glucosidase has prosperous application advantages in the conversion of soybean isoflavones in the feed industry.

Contribution of the β-glucosidase BglC to the onset of the pathogenic lifestyle of Streptomyces scabies

Common scab disease on root and tuber plants is caused by Streptomyces scabies and related species which use the cellulose synthase inhibitor thaxtomin A as the main phytotoxin. Thaxtomin production is primarily triggered by the import of cello-oligosaccharides. Once inside the cell, the fate of the cello-oligosaccharides is dichotomized: (i) the fuelling of glycolysis with glucose for the saprophytic lifestyle through the action of β-glucosidase(s) (BGs); and (ii) elicitation of the pathogenic lifestyle by the inhibition of CebR-mediated transcriptional repression of thaxtomin biosynthetic genes. Here, we investigated the role of scab57721, encoding a putative BG (BglC), in the onset of the pathogenicity of S. scabies. Enzymatic assays showed that BglC was able to release glucose from cellobiose, cellotriose and all other cello-oligosaccharides tested. Its inactivation resulted in a phenotype opposite to that expected, as reduced production of thaxtomin was monitored when the mutant was cultivated on medium containing cello-oligosaccharides as unique carbon source. This unexpected phenotype could be attributed to the highly increased activity of alternative intracellular BGs, probably as a compensation for bglC inactivation, which then prevented cellobiose and cellotriose accumulation to reduce the activity of CebR. In contrast, when the bglC null mutant was cultivated on medium devoid of cello-oligosaccharides, it instead constitutively produced thaxtomin. This observed hypervirulent phenotype does not fit with the proposed model of the cello-oligosaccharide-mediated induction of thaxtomin production, and suggests that the role of BglC in the route to the pathogenic lifestyle of S. scabies is more complex than currently presented.

β-Glucosidase activity in almond seeds

Almond bitterness is the most important trait for breeding programs since bitter-kernelled seedlings are usually discarded. Amygdalin and its precursor prunasin are hydrolyzed by specific enzymes called β-glucosidases. In order to better understand the genetic control of almond bitterness, some studies have shown differences in the location of prunasin hydrolases (PH, the β-glucosidase that degrades prunasin) in sweet and bitter genotypes. The aim of this work was to isolate and characterize different PHs in sweet- and bitter-kernelled almonds to determine whether differences in their genomic or protein sequences are responsible for the sweet or bitter taste of their seeds. RNA was extracted from the tegument, nucellus and cotyledon of one sweet (Lauranne) and two bitter (D05-187 and S3067) almond genotypes throughout fruit ripening. Sequences of nine positive Phs were then obtained from all of the genotypes by RT-PCR and cloning. These clones, from mid ripening stage, were expressed in a heterologous system in tobacco plants by agroinfiltration. The PH activity was detected using the Feigl-Anger method and quantifying the hydrogen cyanide released with prunasin as substrate. Furthermore, β-glucosidase activity was detected by Fast Blue BB salt and Umbelliferyl method. Differences at the sequence level (SNPs) and in the activity assays were detected, although no correlation with bitterness was found.

Heterologous Expression of Rhizobial CelC2 Cellulase Impairs Symbiotic Signaling and Nodulation in Medicago truncatula

The infection of legume plants by rhizobia is tightly regulated to ensure accurate bacterial penetration, infection, and development of functionally efficient nitrogen-fixing root nodules. Rhizobial Nod factors (NF) have key roles in the elicitation of nodulation signaling. Infection of white clover roots also involves the tightly regulated specific breakdown of the noncrystalline apex of cell walls in growing root hairs, which is mediated by Rhizobium leguminosarum bv. trifolii cellulase CelC2. Here, we have analyzed the impact of this endoglucanase on symbiotic signaling in the model legume Medicago truncatula. Ensifer meliloti constitutively expressing celC gene exhibited delayed nodulation and elicited aberrant ineffective nodules, hampering plant growth in the absence of nitrogen. Cotreatment of roots with NF and CelC2 altered Ca²⁺ spiking in root hairs and induction of the early nodulin gene ENOD11. Our data suggest that CelC2 alters early signaling between partners in the rhizobia-legume interaction.

Morphological and Biochemical Assessment of the Cornea in a Gaucher Disease Carrier with Keratoconus

Ocular abnormalities such as corneal opacities and some specific alterations in ocular movements have been described in the neuropathic forms of Gaucher disease. This study was designed to correlate the clinical, morphological and biochemical findings in the corneal button obtained after keratoplasty in a Gaucher disease carrier with keratoconus. Morphologically, the cornea showed keratocytes with marked dilatations of the rough endoplasmic reticulum and intracytoplasmic "dark inclusions"; the acidic lipid profiles presented alterations in the cornea of the Gaucher disease carrier when compared with healthy controls and a clear deficiency in beta-glucosidase activity was detected as well. Our data suggest that the cornea may serve as a good marker of an early target organ in lipid metabolism disorders such as Gaucher's disease.

dsRNA Injection Successfully Inhibited Two Endogenous β-Glucosidases in Coptotermes formosanus (Isoptera: Rhinotermitidae)

Cellulose digestion is an essential process of termites, and it is accomplished by three types of cellulases. β-Glucosidase (BG), one of the critical cellulases responsible for cellulose degradation and glucose production, has been considered as a potential target for pest management strategies. Previous experiments identified two new endogenous BG homologs, CfBG-Ia and CfBG-Ib, in the digestive system of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). The objectives of this study were to assess the impact of RNA interference on CfBG-Ia and CfBG-Ib expression and on termite survival. We tested the expression profiles of worker termites which were injected with gene-specific double-stranded RNA (dsRNA, targeting one gene at a time) and a dsRNA cocktail (targeting CfBG-Ia and CfBG-Ib simultaneously). The expression of CfBG-Ib showed a sharp decline in both dsCfBG-Ib and dsRNA cocktail treatments. The expression of CfBG-Ia reduced quickly and significantly in the dsRNA cocktail treatment; while in dsCfBG-Ia treatment, it decreased on the fifth day. Results showed that treatment with the dsRNA cocktail caused greater inhibition of the transcript expression and a shorter response time. However, the expression of nontarget BG homologs was increased as the target BG homologs were being repressed during the testing period in dsRNA cocktail treatment. These results demonstrate that targeting cellulase-coding genes may be a potential strategy to inhibit termite digestion process, or at least dsRNA cocktails serve as a means for identifying the most susceptible target gene families or biological processes.

Complete Biotransformation of Protopanaxadiol-Type Ginsenosides to 20- O-β-Glucopyranosyl-20( S)-protopanaxadiol Using a Novel and Thermostable β-Glucosidase

The ginsenoside 20- O-β-glucopyranosyl-20( S)-protopanaxadiol, compound K, has attracted much attention in functional food, traditional medicine, and cosmetic industries because of diverse pharmaceutical activities. The effective production of compound K from ginseng extracts has been required. However, an enzyme capable of completely converting all protopanaxadiol (PPD)-type ginsenosides to compound K has not been reported until now. In this study, unlike other enzymes, β-glucosidase from Caldicellulosiruptor bescii was able to hydrolyze sugar moieties such as l-arabinofuranose as well as d-glucose and l-arabinopyranose as the C-20 outer sugar in ginsenosides. Thus, ginsenoside Rc containing l-arabinofuranose can be converted to compound K by only this enzyme. Under the optimized reaction conditions, the enzyme completely converted PPD-type ginsenosides in ginseng extracts to compound K with the highest productivity among the reported results. This is the first report of the enzyme capable of completely converting all PPD-type ginsenosides into compound K.

Effects of silver-graphene oxide nanocomposites on soil microbial communities

Due to the application of silver-graphene oxide (Ag-GO) in diverse fields, it is important to investigate its potential impacts on the environment including soils. In this study, the response of microbial communities in soils treated with Ag-GO synthesized by glucose reduction was determined by analyzing enzyme activities, biomass, and inorganic N concentrations and by pyrosequencing. In soils treated with 0.1-1 mg Ag-GO g^-1 soil, the activities of β-glucosidase, cellobiohydrolase, and xylosidase decreased up to 80% and NO₃^- concentration decreased up to 82% indicating inhibited nitrification. Within the bacterial community, the relative abundance of Acidobacteria and Cyanobacteria in soils treated with Ag-GO were lower than that in control soil. Meanwhile, the relative abundance of AD3 and Firmicutes tended to increase under Ag-GO treatments. These changes in bacterial community composition reflected lowered activities associated with C and N cycling. On the other hand, microbial biomass showed no distinct change in response to Ag-GO treatment. Our study can serve as important basis in establishing guidelines for regulating the release of nanocomposites such as Ag-GO to the soil environment.

Evolution of the biosynthesis of two hydroxyacetophenones in plants

Acetophenones are phenolic metabolites of plant species. A metabolic route for the biosynthesis and release of 2 defence-related hydroxyacetophenones in white spruce (Picea glauca) was recently proposed to involve 3 phases: (a) biosynthesis of the acetophenone aglycons catalysed by a currently unknown set of enzymes, (b) formation and accumulation of the corresponding glycosides catalysed by a glucosyltransferase, and (c) release of the aglycons catalysed by a glucosylhydrolase (PgβGLU-1). We tested if this biosynthetic model is conserved across Pinaceae and land plant species. We assayed and surveyed the literature and sequence databases for possible patterns of the presence of the acetophenone aglycons piceol and pungenol and their glucosides, as well as sequences and expression of Pgβglu-1 orthologues. In the Pinaceae, the 3 phases of the biosynthetic model are present and differences in expression of Pgβglu-1 gene orthologues explain some of the interspecific variation in hydroxyacetophenones. The phylogenetic signal in the metabolite phenotypes was low across species of 6 plant divisions. Putative orthologues of PgβGLU-1 do not form a monophyletic group in species producing hydroxyacetophenones. The biosynthetic model for acetophenones appears to be conserved across Pinaceae, whereas convergent evolution has led to the production of acetophenone glucosides across land plants.

Geissoschizine synthase controls flux in the formation of monoterpenoid indole alkaloids in a Catharanthus roseus mutant

A Catharanthus roseus mutant accumulates high levels of ajmalicine at the expense of catharanthine and vindoline. The altered chemistry depends on increased expression and biochemical activities of strictosidine β-glucosidase and ajmalicine synthase activities and reduced expression and biochemical activity of geissoschizine synthase. The Madagascar periwinkle [Catharanthus roseus (L.) G. Don] is a commercially important horticultural flower species and is a valuable source for several monoterpenoid indole alkaloids (MIAs), such as the powerful antihypertensive drug ajmalicine and the antineoplastic agents, vinblastine and vincristine. While biosynthesis of the common MIA precursor strictosidine and its reactive aglycones has been elucidated, the branch point steps leading to the formation of different classes of MIAs remain poorly characterized. Screening of 3600 ethyl methyl sulfonate mutagenized C. roseus plants using a simple thin-layer chromatography screen yielded a mutant (M2-0754) accumulating high levels of ajmalicine together with significantly lower levels of catharanthine and vindoline. Comparative bioinformatic analyses, virus-induced gene silencing, and biochemical characterization identified geissoschizine synthase, the gateway enzyme that controls flux for the formation of iboga and aspidosperma MIAs. The reduction of geissoschizine synthase transcripts in this high ajmalicine mutant, together with increased transcripts and enzyme activities of strictosidine β-glucosidase and of heteroyohimbine synthase, explains the preferential formation of ajmalicine in the mutant instead of catharanthine and vindoline that accumulates in the wild-type parent. Reciprocal crosses established that that the high ajmalicine phenotype is inherited as a Mendelian recessive trait.

Onion quercetin monoglycosides alter microbial activity and increase antioxidant capacity

The effects on fermentation processes in the digestive tract, the biochemical parameters and antioxidant capacity of blood in rats fed high-fat diets with quercetin (Q) and quercetin with quercetin monoglycosides (Q+MQ) preparations obtained from onion waste were evaluated. Four groups of eight animals were fed for 4 weeks with a control diet (C), a high-fat diet (HF) and high-fat diets with 0.15% addition of Q and Q+MQ preparations. HF caused an increase in alanine transaminase (ALT), non-high-density lipoprotein (non-HDL) and the atherogenic index AII vs. C and a decrease in the proportion of HDL in total cholesterol (TC). Q and Q+MQ showed a tendency to moderate the values aspartate transaminase (P=.087), ALT (P<.05), TC (P=.068), non-HDL cholesterol (P<.05), triglycerides (P=.064) and the atherogenic index AII (P<.05). Q+MQ significantly increased the activity of α-glucosidase (P<.05 vs. HF), β-glucosidase (P<.05) and β-galactosidase (P<.05 vs. C and Q). Q increased activity of β-glucosidase (P<.001 vs. C and HF). Both increased the activity of β-glucuronidase (P<.05 vs. C and HF). Both increased the antioxidant capacity of the hydrophilic fraction in serum (P<.05 vs. C and HF), and Q enhanced that of the lipid fraction (P<.001). Q preparation contained 70% quercetin, and Q+MQ preparation contained 29% quercetin and 13% quercetin monoglycosides, mainly quercetin-4'-glucoside. Both exhibited high antioxidant capacity. Supplementation with Q and Q+MQ increased the enzymatic activity of the intestinal microbiota and the antioxidant capacity of blood and revealed a tendency to improve the blood lipid profile. MQ were particularly effective in stimulating the bacterial enzymatic activity.

Reduced LRRK2 in association with retromer dysfunction in post-mortem brain tissue from LRRK2 mutation carriers

Missense mutations in leucine-rich repeat kinase 2 (LRRK2) are pathogenic for familial Parkinson's disease. However, it is unknown whether levels of LRRK2 protein in the brain are altered in patients with LRRK2-associated Parkinson's disease. Because LRRK2 mutations are relatively rare, accounting for approximately 1% of all Parkinson's disease, we accessioned cases from five international brain banks to investigate levels of the LRRK2 protein, and other genetically associated Parkinson's disease proteins. Brain tissue was obtained from 17 LRRK2 mutation carriers (12 with the G2019S mutation and five with the I2020T mutation) and assayed by immunoblot. Compared to matched controls and idiopathic Parkinson's disease cases, we found levels of LRRK2 protein were reduced in the LRRK2 mutation cases. We also measured a decrease in two other proteins genetically implicated in Parkinson's disease, the core retromer component, vacuolar protein sorting associated protein 35 (VPS35), and the lysosomal hydrolase, glucocerebrosidase (GBA). Moreover, the classical retromer cargo protein, cation-independent mannose-6-phosphate receptor (MPR300, encoded by IGF2R), was also reduced in the LRRK2 mutation cohort and protein levels of the receptor were correlated to levels of LRRK2. These results provide new data on LRRK2 protein expression in brain tissue from LRRK2 mutation carriers and support a relationship between LRRK2 and retromer dysfunction in LRRK2-associated Parkinson's disease brain.

Carbohydrate-binding module assisted purification and immobilization of β-glucosidase onto cellulose and application in hydrolysis of soybean isoflavone glycosides

Complicated purification steps, together with the fact that β-glucosidase has to be tolerant to ethanol restricts the application of β-glucosidase in isoflavone aglycone hydrolyzing process. β-Glucosidase Bgl1A(A24S/F297Y) is a promising enzyme in hydrolyzing isoflavones. In this work, six different carbohydrate-binding modules (CBMs), which were from 3 families, were fused to the C-terminal of Bgl1A(A24S/F297Y), respectively, to simplify the enzyme preparation process. The fusion proteins were expressed in Escherichia coli and adsorbed onto cellulose. The Bgl-CBM24 was found to have the highest immobilization efficiency at room temperature within 1 h adsorption. Notably, 1-g cellulose absorbs up to 254.9±5.7 U of Bgl-CBM24. Interestingly, the immobilized Bgl-CBM24 showed improved ethanol tolerance ability, with the IC50 of 35% (v/v) ethanol. Bgl-CBM24 effectively hydrolyze soybean isoflavone glycosides. The hydrolysis rate of daidzin and gemistin was 85.22±3.24% and 82.14±3.82% within 10 min, with the concentrations of daidzein and genistein increased by 6.36±0.18 mM and 3.98±0.22 mM, respectively. In the repetitive hydrolytic cycles, the concentrations of daidzein and genistein still increased by 3.07±0.24 mM and 1.94±0.34 mM in the fourth cycle with 20% (v/v) ethanol. These results suggest that the immobilized Bgl-CBM24 has excellent potential in the preparation of isoflavone aglycones.

Novel Method to Quantify β-Glucan in Processed Foods: Sodium Hypochlorite Extracting and Enzymatic Digesting (SEED) Assay

Some β-glucans have attracted attention due to their functionality as an immunostimulant and have been used in processed foods. However, accurately measuring the β-glucan content of processed foods using existing methods is difficult. We demonstrate a new method, the Sodium hypochlorite Extracting and Enzymatic Digesting (SEED) assay, in which β-glucan is extracted using sodium hypochlorite, dimethyl sulfoxide, and 5 mol/L sodium hydroxide and then digested into β-glucan fragments using Westase which is an enzyme having β-1,6- and β-1,3 glucanase activity. The β-glucan fragments are further digested into glucose using exo-1,3-β-d-glucanase and β-glucosidase. We measured β-glucan comprising β-1,3-, -1,6-, and -1,(3),4- bonds in various polysaccharide reagents and processed foods using our novel method. The SEED assay was able to quantify β-glucan with good reproducibility, and the recovery rate was >90% for food containing β-glucan. Therefore, the SEED assay is capable of accurately measuring the β-glucan content of processed foods.

Search for independent (β/α)4 subdomains in a (β/α)8 barrel β-glucosidase

Proteins that fold as (β/α)₈ barrels are thought to have evolved from half-barrels that underwent duplication and fusion events. The evidence is particularly clear for small barrels, which have almost identical halves. Additionally, computational calculations of the thermodynamic stability of these structures in the presence of denaturants have revealed that (β/α)₈ barrels contain two subunits or domains corresponding to half-barrels. Hence, within (β/α)₈ barrels, half-barrels are self-contained units. Here, we tested this hypothesis using β-glucosidase from the bacterium Thermotoga maritima (bglTm), which has a (β/α)₈ barrel structure. Mutations were introduced to disrupt the noncovalent contacts between its halves and reveal the presence of two domains within bglTm, thus resulting in the creation of mutants T1 (containing W12A and I217A mutations) and T2 (containing W12A, H195A, I217A and F404A mutations). Mutants T1 and T2 were properly folded, as indicated by their fluorescence spectra and enzyme kinetic parameters. T1 and wild-type bglTm were equally stable, as shown by the results of thermal inactivation, differential scanning fluorimetry and guanidine hydrochloride denaturation experiments. However, T2 showed a first-order inactivation at 80°C, a single melting temperature of 82°C and only one transition concentration (c₅₀) in 2.4 M guanidine hydrochloride. Additionally, T1 and T2 exhibited a cooperative denaturation process that followed a two-state model (m-values equal to 1.4 and 1.6 kcal/mol/M, respectively), similar to that of wild-type bglTm (1.2 kcal/mol/M). Hence, T1 and T2 each denatured as a single unit, although they contained different degrees of disruption between their halves. In conclusion, bglTm halves are equivalent in terms of their thermal and chemical stability; thus, their separate contributions to (β/α)₈ barrel unfolding cannot be disentangled.

An L213A variant of β-glycosidase from Sulfolobus solfataricus with increased α-L-arabinofuranosidase activity converts ginsenoside Rc to compound K

Compound K (C-K) is a crucial pharmaceutical and cosmetic component because of disease prevention and skin anti-aging effects. For industrial application of this active compound, the protopanaxadiol (PPD)-type ginsenosides should be transformed to C-K. β-Glycosidase from Sulfolobus solfataricus has been reported as an efficient C-K-producing enzyme, using glycosylated PPD-type ginsenosides as substrates. β-Glycosidase from S. solfataricus can hydrolyze β-d-glucopyranoside in ginsenosides Rc, C-Mc₁, and C-Mc, but not α-l-arabinofuranoside in these ginsenosides. To determine candidate residues involved in α-l-arabinofuranosidase activity, compound Mc (C-Mc) was docking to β-glycosidase from S. solfataricus in homology model and sequence was aligned with β-glycosidase from Pyrococcus furiosus that has α-l-arabinofuranosidase activity. A L213A variant β-glycosidase with increased α-l-arabinofuranosidase activity was selected by substitution of other amino acids for candidate residues. The increased α-l-arabinofuranosidase activity of the L213A variant was confirmed through the determination of substrate specificity, change in binding energy, transformation pathway, and C-K production from ginsenosides Rc and C-Mc. The L213A variant β-glycosidase catalyzed the conversion of Rc to Rd by hydrolyzing α-l-arabinofuranoside linked to Rc, whereas the wild-type β-glycosidase did not. The variant enzyme converted ginsenosides Rc and C-Mc into C-K with molar conversions of 97%, which were 1.5- and 2-fold higher, respectively, than those of the wild-type enzyme. Therefore, protein engineering is a useful tool for enhancing the hydrolytic activity on specific glycoside linked to ginsenosides.

Quantification of nitrogen in the liquid fraction and in vitro assessment of lysine bioavailability in the solid fraction of soybean meal hydrolysates

Soybean meal (SBM) is a product generated from the manufacture of soybean oil and has the potential for use as a source of fermentable sugars for ethanol production or as a protein source for animal feeds. Knowing the levels of nitrogen available from ammonium is a necessary element of the ethanolic fermentation process while identifying the levels of essential amino acids such as lysine is important in determining usage as a feed source. As such the purpose of this study was to quantify total nitrogen and ammonium in the liquid fraction of hydrolyzed SBM and to evaluate total and bioavailable lysine in the solid fraction of the hydrolyzed SBM. The effects of acid concentration, cellulase and β-glucosidase on total and ammonium nitrogen were studied with analysis indicating that higher acid concentrations increased nitrogen compounds with ammonium concentrations ranging from 0.20 to 1.24 g L-1 while enzymatic treatments did not significantly increase nitrogen levels. Total and bioavailable lysine was quantified by use of an auxotrophic gfpmut3 E.coli whole-cell bioassay organism incapable of lysine biosynthesis. Acid and enzymatic treatments were applied with lysine bioavailability increasing from a base of 82% for untreated SBM to up to 97%. Our results demonstrated that SBM has the potential to serve in ethanolic fermentation and as an optimal source essential amino acid lysine.

Enhanced cell-surface display of a heterologous protein using SED1 anchoring system in SED1-disrupted Saccharomyces cerevisiae strain

Yeast displaying enzymes on the cell surface are used for developing whole-cell biocatalysts. High enzyme activity on the cell surface is required in certain applications such as direct ethanol production from lignocellulosic materials. However, the cell surface enzyme activity is limited by several factors, one of which is the protein amount of the yeast cell wall. In this study, we attempted to improve the incorporation capacity of a displayed heterologous enzyme by disrupting a native cell-wall protein. β-Glucosidase (BGL1) from Aspergillus aculeatus was fused with Saccharomyces cerevisiae Sed1 and displayed on the cell surface of S. cerevisiae BY4741 strain and its SED1 disruptant. Sed1 is one of the most abundant stationary phase yeast cell wall protein. A time course analysis revealed that BGL1 activity of the control strain reached saturation after 48 h of cultivation. In contrast, the BGL1 activity of the SED1 disruptant increased until 72 h of cultivation and was 22% higher than that of the control strain. We also performed relative quantification of cell wall proteins of these strains by nanoscale ultra pressure liquid chromatography electrospray ionization quadrupole time-of-flight tandem mass spectrometry (nano-UPLC-MS^E). The amount of the cell wall-associated BGL1 per unit dry cell-weight of the SED1 disruptant was 19% higher than that of the control strain. These results suggested that the incorporation capacity of the cell wall for BGL1 was increased by disruption of SED1. Disruption of SED1 would be a promising approach for improving display efficiency of heterologous protein fused with Sed1.

Engineering the GH1 β-glucosidase from Humicola insolens: Insights on the stimulation of activity by glucose and xylose

The activity of the GH1 β-glucosidase from Humicola insolens (Bglhi) against p-nitrophenyl-β-D-glucopyranoside (pNP-Glc) and cellobiose is enhanced 2-fold by glucose and/or xylose. Kinetic and transglycosylation data showed that hydrolysis is preferred in the absence of monosaccharides. Stimulation involves allosteric interactions, increased transglycosylation and competition of the substrate and monosaccharides for the -1 glycone and the +1/+2 aglycone binding sites. Protein directed evolution has been used to generate 6 mutants of Bglhi with altered stimulation patterns. All mutants contain one of three substitutions (N235S, D237V or H307Y) clustered around the +1/+2 aglycone binding sites. Two mutants with the H307Y substitution preferentially followed the transglycosylation route in the absence of xylose or glucose. The strong stimulation of their pNP-glucosidase and cellobiase activities was accompanied by increased transglycosylation and higher monosaccharide tolerance. The D237V mutation favoured hydrolysis over transglycosylation and the pNP-glucosidase activity, but not the cellobiase activity, was stimulated by xylose. The substitution N235S abolished the preference for hydrolysis or transglycosylation; the cellobiase, but not the pNP-glucosidase activity of the mutants was strongly inhibited by xylose. Both the D237V and N235S mutations lowered tolerance to the monosaccharides. These results provide evidence that the fine modulation of the activity of Bglhi and mutants by glucose and/or xylose is regulated by the relative affinities of the glycone and aglycone binding sites for the substrate and the free monosaccharides.

A light-sensitive mutation in Arabidopsis LEW3 reveals the important role of N-glycosylation in root growth and development

Plant roots have the potential capacity to grow almost indefinitely if meristematic and lateral branching is sustained. In a genetic screen we identified an Arabidopsis mutant showing limited root growth (lrg1) due to defects in cell division and elongation in the root meristem. Positional cloning determined that lrg1 affects an alpha-1,2-mannosyltransferase gene, LEW3, involved in protein N-glycosylation. The lrg1 mutation causes a synonymous substitution that alters the correct splicing of the fourth intron in LEW3, causing a mix of wild-type and truncated protein. LRG1 RNA missplicing in roots and short root phenotypes in lrg1 are light-intensity dependent. This mutation disrupts a GC-base pair in a three-base-pair stem with a four-nucleotide loop, which seems to be necessary for correct LEW3 RNA splicing. We found that the lrg1 short root phenotype correlates with high levels of reactive oxygen species and low pH in the apoplast. Proteomic analyses of N-glycosylated proteins identified GLU23/PYK10 and PRX34 as N-glycosylation targets of LRG1 activity. The lrg1 mutation reduces the positive interaction between Arabidopsis and Serendipita indica. A prx34 mutant showed a significant reduction in root growth, which is additive to lrg1. Taken together our work highlights the important role of N-glycosylation in root growth and development.

Production of steviol from steviol glucosides using β-glucosidase from a commercial pectinase, Sumizyme PX

OBJECTIVE

To purify and characterize a specific enzyme from a commercial pectinase for the production of steviol from stevioside (Ste) without adding organic solvent and to improve steviol production.

RESULTS

Commercial Sumizyme PX converted Ste to steviol with a yield of 98%. β-Glucosidase from Sumizyme PX (βglyPX) was purified in three steps with 12.5-fold purification and 51% yield. The specific activity of the purified βglyPX was 141 U/mg. The molecular weight of βglyPX was ~ 116 kDa on SDS-PAGE. Its optimum activity was at pH 3.5 and 65 °C. It was stable for 12 h up to 55 °C and for 24 h at pH 2-9.5. K _m values of βglyPX for pNPGal, oNPGlc, lactose, and Ste were 2.4, 0.7, 18, and 7.8 mM, respectively. The optimum conditions for steviol production were 55 °C, 900 U/ml, 80 mg Ste/ml, 12 h.

CONCLUSION

βglyPX contains great potential for industrial steviol production from Ste.

A Fluorescence Polarization Activity-Based Protein Profiling Assay in the Discovery of Potent, Selective Inhibitors for Human Nonlysosomal Glucosylceramidase

Human nonlysosomal glucosylceramidase (GBA2) is one of several enzymes that controls levels of glycolipids and whose activity is linked to several human disease states. There is a major need to design or discover selective GBA2 inhibitors both as chemical tools and as potential therapeutic agents. Here, we describe the development of a fluorescence polarization activity-based protein profiling (FluoPol-ABPP) assay for the rapid identification, from a 350+ library of iminosugars, of GBA2 inhibitors. A focused library is generated based on leads from the FluoPol-ABPP screen and assessed on GBA2 selectivity offset against the other glucosylceramide metabolizing enzymes, glucosylceramide synthase (GCS), lysosomal glucosylceramidase (GBA), and the cytosolic retaining β-glucosidase, GBA3. Our work, yielding potent and selective GBA2 inhibitors, also provides a roadmap for the development of high-throughput assays for identifying retaining glycosidase inhibitors by FluoPol-ABPP on cell extracts containing recombinant, overexpressed glycosidase as the easily accessible enzyme source.

Mucilaginibacter ginsenosidivorans sp. nov., Isolated from Soil of Ginseng Field

A Gram-reaction-negative, aerobic, nonmotile, nonspore-forming, and rod-shaped bacterial strain designated Gsoil 3017^T was isolated from soil of ginseng field and investigated by phenotypic and phylogenetic analyses. Strain Gsoil 3017^T grew at 10-37 °C (optimal growth at 30 °C) and at pH 5.5-8.0 (optimal growth at pH 7) on R2A and nutrient agar without additional NaCl as a supplement. Strain Gsoil 3017^T possessed β-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb₁, Rc, and Rd (the three dominant active components of ginseng) to F₂ and C-K, respectively. Based on 16S rRNA gene phylogeny, the novel strain represents a new branch within the genus Mucilaginibacter family Sphingobacteriaceae, and clusters with Mucilaginibacter frigoritolerans FT22^T (95.6%) and Mucilaginibacter gotjawali SA3-7^T (95.6%). The G+C content of the genomic DNA was 48.7%. The predominant respiratory quinone was MK-7, and the major fatty acids were iso-C_15:0, iso-C_17:0 3-OH, and summed feature 3 (comprising C_16:1 ω6c and/or C_16:1 ω7c). The major polar lipid was phosphatidylethanolamine. Strain Gsoil 3017^T could be differentiated genotypically and phenotypically from other type strains of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter ginsenosidivorans sp. nov. is proposed, with the type strain Gsoil 3017^T (=KACC 14954^T = JCM 17081^T).

[Responses of Extracellular Enzymes to Nitrogen Application in Rice of Various Ages with Rhizosphere and Bulk Soil]

Ecological enzyme activities are closely relevant to the carbon and nitrogen decomposition and mineralization of paddy soils, which can reflect the growth and metabolism of microorganisms. In order to clarify the response to nitrogen application by different enzymes in the rhizosphere and bulk soil of rice, the rhizosphere and bulk soil were identified using a rhizosphere bag. In addition, the β-1,4-glucosidase (BG) enzyme; β-1,4-N-acetylglucosaminidase (NAG) enzyme; and the effects of the rhizosphere, nitrogen application, and growth period on soil enzyme activities were analyzed. The results showed that the activity of the BG enzyme decreased by 7.4-13.5 nmol·(g·h)^-1 in the jointing stage and increased by 7.0-31.4 nmol·(g·h)^-1 in the maturity stage, and the activity of the BG enzyme in the rhizosphere and bulk soil also changed with the growth period of rice.compared with no nitrogen fertilizer, nitrogen application increased NAG enzyme activity by 1.1 times and rhizosphere soil by 0.3 times in the bulk soil in the maturity stage. Nitrogen application and growth period had significant effects on soil BG enzyme activity, whereas the interaction within rice growth stage, nitrogen application, and rhizosphere effect had significant effects on NAG enzyme activity. The result of RDA showed that the soil microbial biomass carbon (MBC) and dissolved organic carbon (DOC) contents mainly affected the activity of extracellular enzymes in the rice rhizosphere soil, whereas the activities of enzymes in the rhizosphere soil were mainly affected by microbial biomass nitrogen (MBN) and NH₄⁺-N. The relationships between soil enzyme activity and various factors are complex, and the effects of nitrogen addition on microbial community composition needs to be considered after accounting for plant physiological characteristics, soil enzyme activity, and soil characteristics.

Molecular cloning, characterization and in silico analysis of a thermostable β-glucosidase enzyme from Putranjiva roxburghii with a significant activity for cellobiose

The native Putranjiva roxburghii family 1 glycoside hydrolase enzyme showed β-D-fucosidase activity in addition to β-D-glucosidase and β-D-galactosidase activities reported in our previous study. A single step concanvalin A affinity chromatography for native PRGH1 improved the yield and reduced the purification time. The PRGH1 gene was cloned and overexpressed in E. coli. The full length gene contained an ORF of 1617 bp encoding a polypeptide of 538 amino acids. The amino acid sequence of PRGH1 showed maximum similarities to β-glucosidases and myrosinases. Both native and recombinant protein showed maximum hydrolytic activity for pNP-Fuc followed by pNP-Glc and pNP-Gal. Significant enzyme activity was also observed for cellobiose, however it decreased with increase in chain-length for glycan substrates. The enzyme showed significant resistant to D-glucose concentration up to 500 mM. Mutational studies confirmed the predicted catalytic acid/base Glu173 and nucleophile Glu389 as key residues for its activity. Moreover, Glu446 and Asn172 played essential role in substrate binding by interacting with the -1 subsite of substrates. Bioinformatic analysis suggested the possible reasons for the broad substrate specificity and other properties of the enzyme. PRGH1 had high sequence similarity towards S-glucosidase and may be involved in defence. The broad specificity, catalytic efficiency and thermostability make PRGH1 potentially an important industrial enzyme.

Systematic studies of the interactions between a model polyphenol compound and microbial β-glucosidases

Lignin is a major obstacle for cost-effective conversion of cellulose into fermentable sugars. Non-productive adsorption onto insoluble lignin fragments and interactions with soluble phenols are important inhibition mechanisms of cellulases, including β-glucosidases. Here, we examined the inhibitory effect of tannic acid (TAN), a model polyphenolic compound, on β-glucosidases from the bacterium Thermotoga petrophila (TpBGL1 and TpBGL3) and archaeon Pyrococcus furiosus (PfBGL1). The results revealed that the inhibition effects on β-glucosidases were TAN concentration-dependent. TpBGL1 and TpBGL3 were more tolerant to the presence of TAN when compared with PfBGL1, while TpBGL1 was less inhibited when compared with TpBGL3. In an attempt to better understand the inhibitory effect, the interaction between TAN and β-glucosidases were analyzed by isothermal titration calorimetry (ITC). Furthermore, the exposed hydrophobic surface areas in β-glucosidases were analyzed using a fluorescent probe and compared with the results of inhibition and ITC. The binding constants determined by ITC for the interactions between TAN and β-glucosidases presented the same order of magnitude. However, the number of binding sites and exposed hydrophobic surface areas varied for the β-glucosidases studied. The binding between TAN and β-glucosidases were driven by enthalpic effects and with an unfavorable negative change in entropy upon binding. Furthermore, the data suggest that there is a high correlation between exposed hydrophobic surface areas and the number of binding sites on the inhibition of microbial β-glucosidases by TAN. These studies can be useful for biotechnological applications.

The C-Domain of Oleuropein β-Glucosidase Assists in Protein Folding and Sequesters the Enzyme in Nucleus

Oleuropein, a terpene-derived glycosylated secoiridoid biosynthesized exclusively by members of the Oleaceae family, is involved in a two-component defense system comprising a β-glucosidase that activates oleuropein into a toxic glutaraldehyde-like structure. Oleuropein and its deglycosylated derivatives have high pharmaceutical interest. In this study we determined that the in planta heterologous expressed OeGLU, an oleuropein-specific β-glucosidase from olive (Olea europaea), had enzymatic kinetics similar to the olive native enzyme. The C terminus encompassing the nuclear localization signal sequesters the enzyme in the nucleus, and predetermines the protein-protein recognition and homodimerization. Biochemical analysis revealed that OeGLU is a homomultimer with high M_r In silico prediction modeling of the complex structure and bimolecular fluorescence complementation analyses revealed that the C terminus of OeGLU is essential for the proper assembly of an octameric form, a key conformational feature that determines the activity of the enzyme. Our results demonstrate that intrinsic characteristics of the OeGLU ensure separation from oleuropein and keep the dual-partner defensive system conditionally inactive. Upon cell destruction, the dual-partner defense system is activated and olive massively releases the arsenal of defense.

Production of bioactive hydrolysate using protease, β-glucosidase and α-amylase of Bacillus spp. isolated from kinema

The aim of this study was the production of soybean bioactive hydrolysate using Bacillus spp. isolated from kinema. Totally 251 bacteria isolated from kinema samples, collected at different time period were screened for protease, β-glucosidase and α-amylase activities and further identified by ARDRA based grouping followed by analysis of 16S rRNA gene sequence similarity. The results showed that Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus licheniformis were the major Bacillus species. Twelve fermentative strains belonging to these groups and having high protease, α-amylase and β-glucosidase activity were used for solid state fermentation. The best strains for soybean fermentation that result in production of protein hydrolysates rich in polyphenols that have higher bioactivity were B. subtilis KN12C, B. amyloliquefaciens KN2G and B. licheniformis KN13C. Potential isolates can be applied for the production of soybean hydrolysates and can also find application in production of value added products from by-products of soybean processing industries.

Trichoderma virens β-glucosidase I (BGLI) gene; expression in Saccharomyces cerevisiae including docking and molecular dynamics studies

BACKGROUND

Cellulose, a linear polymer of β 1-4, linked glucose, is the most abundant renewable fraction of plant biomass (lignocellulose). It is synergistically converted to glucose by endoglucanase (EG) cellobiohydrolase (CBH) and β-glucosidase (BGL) of the cellulase complex. BGL plays a major role in the conversion of randomly cleaved cellooligosaccharides into glucose. As it is well known, Saccharomyces cerevisiae can efficiently convert glucose into ethanol under anaerobic conditions. Therefore, S.cerevisiae was genetically modified with the objective of heterologous extracellular expression of the BGLI gene of Trichoderma virens making it capable of utilizing cellobiose to produce ethanol.

RESULTS

The cDNA and a genomic sequence of the BGLI gene of Trichoderma virens was cloned in the yeast expression vector pGAPZα and separately transformed to Saccharomyces cerevisiae. The size of the BGLI cDNA clone was 1363 bp and the genomic DNA clone contained an additional 76 bp single intron following the first exon. The gene was 90% similar to the DNA sequence and 99% similar to the deduced amino acid sequence of 1,4-β-D-glucosidase of T. atroviride (AC237343.1). The BGLI activity expressed by the recombinant genomic clone was 3.4 times greater (1.7 x 10-3 IU ml-1) than that observed for the cDNA clone (5 x 10-4 IU ml-1). Furthermore, the activity was similar to the activity of locally isolated Trichoderma virens (1.5 x 10-3 IU ml-1). The estimated size of the protein was 52 kDA. In fermentation studies, the maximum ethanol production by the genomic and the cDNA clones were 0.36 g and 0.06 g /g of cellobiose respectively. Molecular docking results indicated that the bare protein and cellobiose-protein complex behave in a similar manner with considerable stability in aqueous medium. The deduced binding site and the binding affinity of the constructed homology model appeared to be reasonable. Moreover, it was identified that the five hydrogen bonds formed between the amino acid residues of BGLI and cellobiose are mainly involved in the integrity of enzyme-substrate association.

CONCLUSIONS

The BGLI activity was remarkably higher in the genomic DNA clone compared to the cDNA clone. Cellobiose was successfully fermented into ethanol by the recombinant S.cerevisiae genomic DNA clone. It has the potential to be used in the industrial production of ethanol as it is capable of simultaneous saccharification and fermentation of cellobiose. Homology modeling, docking studies and molecular dynamics simulation studies will provide a realistic model for further studies in the modification of active site residues which could be followed by mutation studies to improve the catalytic action of BGLI.

Bioactivity Improvement of Olea europaea Leaf Extract Biotransformed by Wickerhamomyces anomalus Enzymes

Olive leaves represent a quantitatively significant by-product of agroindustry. They are rich in phenols, mainly oleuropein, which can be hydrolyzed into several bioactive compounds, including hydroxytyrosol. In this study, water extract from olive leaves 'Biancolilla' was analyzed for polyphenol profile, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and protective effect on differentiated Caco-2 cells. The efficacy of two enzymatic treatments in promoting the release of bioactive phenols was investigated: a) enzymatic extract from Wickerhamomyces anomalus, characterized by β-glucosidase and esterase activities; b) commercial β-glucosidase. Composition and bioactivity of the resulting extracts were compared. The results showed that the yeast-treated extract presented hydroxytyrosol content and DPPH radical scavenging activity comparable to those obtained using commercial β-glucosidase; however, it was showed the additional presence of hydroxycinnamic acids. In experiments on Caco-2 cells, the leaf extracts promoted the recovery of cell membrane barrier at different minimum effective concentrations. The high specificity of W. anomalus enzymatic extract may represent an effective tool for the release of bioactive phenols from olive by-products.