Comparison of three different thermophilic beta-glucosidases for baicalin transformation / 中国中药杂志

Three different beta-glycosidase sequences of Ttebgl3, Tpebgl1 and Tpengl3 from Thermotoga thermarum DSM 5069 and Thermotoga petrophila RKU-1 were analyzed. Also, the influence of temperature, pH, concentration of DMSO, metal ions and kinetic constant on catalytic conversion of baicalin had been compared. The results indicated that the optimal pH and optimum temperature for transformation of baicalin was 4.5 85 °C, 5.0 80 °C and 5.5 80 °C, respectively. The family GH3 beta-glycosidase Ttebgl3 and Tpebgl3 had the better DMSO tolerance. The activation effect of the metal ions on the catalytic conversion of baicalin was not obvious, and the inhibition of the GH3 family beta glucosidase was significantly stronger than that of the GH1 family. The kinetic constants of three different beta-glucosidases catalyzed baicalin were significantly different. The Km and Vmax values of Tpebgl1, Tpebgl3 and Ttebgl3 were 0.029 2 mmol·L⁻¹ 4.85 U·mg⁻¹, 0.268 6 mmol·L⁻¹ 121.04 U·mg⁻¹ and 0.391 8 mmol·L⁻¹ 308.90 U·mg⁻¹, respectively. Family GH3 beta-glycosidase converted more baicalin than family GH1 with the optimal conditions, 0.02 g baicalin, and the conversion rate was 68%, 97.3%, 97.31% respectively. The results of the study provided a guarantee for the transformation of baicalin.

Enhancement of beta-Glucosidase Activity from a Brown Rot Fungus Fomitopsis pinicola KCTC 6208 by Medium Optimization

beta-Glucosidase, which hydrolyzes cellobiose into two glucoses, plays an important role in the process of saccharification of the lignocellulosic biomass. In this study, we optimized the activity of beta-glucosidase of brown-rot fungus Fomitopsis pinicola KCTC 6208 using the response surface methodology (RSM) with various concentrations of glucose, yeast extract and ascorbic acid, which are the most significant nutrients for activity of beta-glucosidase. The highest activity of beta-glucosidase was achieved 3.02% of glucose, 4.35% of yeast extract, and 7.41% ascorbic acid where ascorbic acid was most effective. The maximum activity of beta-glucosidase predicted by the RSM was 15.34 U/mg, which was similar to the experimental value 14.90 U/mg at the 16th day of incubation. This optimized activity of beta-glucosidase was 23.6 times higher than the preliminary activity value, 0.63 U/mg, and was also much higher than previous values reported in other fungi strains. Therefore, a simplified medium supplemented with a cheap vitamin source, such as ascorbic acid, could be a cost effective mean of increasing beta-glucosidase activity.

Bioconversion of Ginsenosides from Red Ginseng Extract Using Candida allociferrii JNO301 Isolated from Meju

Red ginseng (Panax ginseng), a Korean traditional medicinal plant, contains a variety of ginsenosides as major functional components. It is necessary to remove sugar moieties from the major ginsenosides, which have a lower absorption rate into the intestine, to obtain the aglycone form. To screen for microorganisms showing bioconversion activity for ginsenosides from red ginseng, 50 yeast strains were isolated from Korean traditional meju (a starter culture made with soybean and wheat flour for the fermentation of soybean paste). Twenty strains in which a black zone formed around the colony on esculin-yeast malt agar plates were screened first, and among them 5 strains having high beta-glucosidase activity on p-nitrophenyl-beta-D-glucopyranoside as a substrate were then selected. Strain JNO301 was finally chosen as a bioconverting strain in this study on the basis of its high bioconversion activity for red ginseng extract as determined by thin-layer chromatography (TLC) analysis. The selected bioconversion strain was identified as Candida allociferrii JNO301 based on the nucleotide sequence analysis of the 18S rRNA gene. The optimum temperature and pH for the cell growth were 20~30degrees C and pH 5~8, respectively. TLC analysis confirmed that C. allociferrii JNO301 converted ginsenoside Rb1 into Rd and then into F2, Rb2 into compound O, Rc into compound Mc1, and Rf into Rh1. Quantitative analysis using high-performance liquid chromatography showed that bioconversion of red ginseng extract resulted in an increase of 2.73, 3.32, 33.87, 16, and 5.48 fold in the concentration of Rd, F2, compound O, compound Mc1, and Rh1, respectively.

Biochemical Characterization of an Extracellular beta-Glucosidase from the Fungus, Penicillium italicum, Isolated from Rotten Citrus Peel

A beta-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and 60degrees C, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and 65degrees C, respectively. Its activity was inhibited by 47% by 5 mM Ni2+. The enzyme exhibited hydrolytic activity for p-nitrophenyl-beta-D-glucopyranoside (pNP-Glu), p-nitrophenyl-beta-D-cellobioside, p-nitrophenyl-beta-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl-beta-D-lactopyranoside, p-nitrophenyl-beta-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a beta-glucosidase. The kcat/Km (s-1 mM-1) values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for beta-glucosidases. Non-competitive inhibition of the enzyme by both glucose (Ki = 8.9 mM) and glucono-delta-lactone (Ki = 11.3 mM) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of beta-glucosidase by glucose and glucono-delta-lactone.

Enhancement of escherichia coli cellulolytic activity by co-production of beta-glucosidase and endoglucanase enzymes

Cellulase is a group of enzymes (endoglucanase, exoglucanase and beta-glucosidase) required for cellulosic feedstock hydrolysis during bioethanol production. The use of recombinant cellulase is a strategy to reduce the enzyme cost. In this context, the present work describes the construction of a cellulase expression vector (pEglABglA), which allowed constitutive co-expression of endoglucanase A (EglA) from an endophytic Bacillus pumilus and the hyperthermophilic beta-glucosidase A (BglA) from Fervidobacterium sp. in Escherichia coli. When compared to the non-modified strain DH5 alpha, the recombinant Escherichia coli DH5 alpha (pEglABglA) reduced fivefold the viscosity of the carboxymethylcellulose medium (CMC-M). Also, it presented almost 30-fold increase in reducing sugar released from CMC-M, enabling the recombinant strain to grow using CMC as the sole carbon and energy source. When cultivated in rich media, specific growth rates of recombinant E. coli strains BL21, JM101 and Top10 were higher than those of DH5 alpha and DH10B strains. The constructed plasmid (pEglABglA) can be used as backbone for further cellulase gene addition, which may enhance even more E. coli cellulolytic capacity and growth rate.

Purification and characterization of beta-glucosidase from Melanocarpus sp. MTCC 3922

This study reports the purification and characterization of beta-glucosidase from a newly isolated thermophilic fungus, Melanocarpus sp. Microbial Type Culture Collection (MTCC) 3922. The molecular weight of beta-glucosidase was determined to be ~ 92 and 102 kDa with SDS PAGE and gel filtration, respectively, and pI of ~ 4.1. It was optimally active at 60 C and pH 6.0, though was stable at 50 C and pH 5.0 - 6.0. The presence of DTT, mercaptoethanol and metal ions such as Na+, K+, Ca2+, Mg2+and Zn2+ positively influenced the activity of beta-glucosidase but the activity was inhibited in the presence of CuSO4. beta-Glucosidase recognized pNP- beta-glucopyranoside (pNPG) as the preferred substrate, and showed very low affinity for pNP- beta-D-cellobioside. Km and Vmax for the hydrolysis of pNPG by beta-glucosidase was calculated as 3.3 mM and 43.68 ‘molmin-1mg protein-1, respectively and k cat was quantified as 4 x 10³ min-1. beta-Glucosidase activity was enhanced appreciably in the presence of alcohols (methanol and ethanol) moreover, purified beta-glucosidase showed putative transglycosylation activity that was positively catalyzed in presence of methanol as an acceptor molecule

Comparison of Dyes for Easy Detection of Extracellular Cellulases in Fungi

To evaluate which dye is effective in a plate assay for detecting extracellular cellulase activity produced by fungi, four chromogenic dyes including remazol brilliant blue, phenol red, congo red, and tryphan blue, were compared using chromagenic media. For the comparison, 19 fungal species belonging to three phyla, ascomycota, basidiomycota, and zygomycota were inoculated onto yeast nitrogen-based media containing different carbon substrates such as cellulose (carboxylmethyl and avicel types) and cellobiose labeled with each of the four dyes. Overall, the formation of clear zone on agar media resulting from the degradation of the substrates by the enzymes secreted from the test fungi was most apparent with media containing congo red. The detection frequency of cellulase activity was also most high on congo red-supplemented media. The results of this study showed that congo red is better dye than other three dyes in a plate assay for fungal enzyme detection.

Detection of Extracellular Enzyme Activity in Penicillium using Chromogenic Media

A total of 106 Penicillium species were tested to examine their ability of degrading cellobiose, pectin and xylan. The activity of beta-glucosidase was generally strong in all the Penicillium species tested. P. citrinum, P. charlesii, P. manginii and P. aurantiacum showed the higher ability of producing beta-glucosidase than other tested species. Pectinase activity was detected in 24 Penicillium species. P. paracanescens, P. sizovae, P. sartoryi, P. chrysogenum, and P. claviforme showed strong pectinase activity. In xylanase assay, 84 Penicillium species showed activity. Strong xylanase activity was detected from P. megasporum, P. sartoryi, P. chrysogenum, P. glandicola, P. discolor, and P. coprophilum. Overall, most of the Penicillium species tested showed strong beta-glucosidase activity. The degree of pectinase and xylanase activity varied depending on Penicillium species.

Two Cases of Progressive Myoclonus Epilepsy due to Gaucher's Disease, Type 3

Gaucher's disease is an autosomal recessive disorder caused by a deficiency of beta-glucosidase (glucocerebrosidase) which results in an accumulation of glucocerebroside in various organs and tissues. Type 3 (juvenile or subacute neuro-pathic) Gaucher's disease, presented here as progressive myoclonus epilepsy, occurs more rarely than type 1 (adult or nonneuropathic) or type 2 (infantile or neuropathic) Gaucher's disease. Two patients (brother and sister) with type 3 Gaucher's disease had or was expected to develop typical features of progressive myoclonus epilepsy: myoclonus, seizures, dementia, and cerebellar dysfunction. One of them showed Gaucher cells in a liver biopsy specimen and decreased beta-glucosidase activity (14% of normal) in the cultured skin fibroblasts, which confirmed the clinical diagno-sis of type 3 Gaucher's disease.