应用粘度测定法测定麦芽中内源β-葡聚糖酶的活性

用于测定麦芽中内源β－葡聚糖酶活性的粘度测定法已由酿造学会分析委员会做合作试验。共有10个实验室参加试验，分析了5对麦芽样品，范围为176至1238IRV单位。重复性（r95）值为22至122IRV单位，重现性（R95）值为93至650IRV单位。结果表明，取决于内源β－箭聚精酶的活性水平的是R95而不是r95.总精确度值是：r95为76．8，R95为0．506X平均值十4．786。因此决定将这一方法编入IOB分析法里，但要注意这次试验和以往的合作试验中得到的精确度值都较差。

Enzymatic Transformation of Notoginsenoside Fe by β-Glucanase

Aim An industrial enzyme β-glucanase was used to transfortn notoginsenoside Fe for the first time. Methods Notoginsenoside Fe was isolated from the leave saponin of Panax notoginseng （Burk.） Chen FH. The enzymatically transformed compounds were detected by HPLC and two transformed compounds were identified as 20 （S） -protopanaxadiol-20- O- α-L-arabinofuranosyl （ 1→6 ） - β-gluco- pyranoside, ginsenoside-Mc） and 20（S）-protopanaxadiol-20-O-β-D-glucopyranoside compound-K （C-K） respectively on the basis of their ^1H NMR and ^13 C NMR spectral data. Results Based on the enzymolytic kinetic curve, the transformation rate of notoginsenoside Fe reached 95% after 24 h. Conclusion The enzymatic transformation pathway of notoginsenoside Fe by β-glucanase has been proposed as notoginsenoside Fe→ginsenoside Mc→C-K.

Increase of β -1, 3-Glucanase and Chitinase Activities in Cotton Callus Cells Treated by Salicylic Acid and Toxin of Verticillium dahliae

The different resistance of cotton (Gossypium hirsutum L.) cultivars to crude toxin of Verticillium dah/iae(VD) was correlated with the activities of chitinase and β-1, 3-glucanase in callus cells. The activities of chitinase and β-1, 3-glucanase in the callus cells treated with the VD-toxin were increased to the higher level at earlier time point in resistant cultivars than these in the susceptible cultivars. Exogenous salicylic acid (SA) induced the accumulation of chitinase and β -1,3-glucanase, which resulted in the resistance of callus cells to the VD. toxin. Western blot using a polyclonal antibody against β -1,3-glucanase identified 28 kD protein that was induced by VD-toxin, SA, or VD-toxin plus SA.

Role of Wall-bound β-Glucanases in Regulating Tip-growth of Lilium longiflorum Pollen Tubes

Glucanases were found in the cell wall of Lilium longiflorum Thunb. pollen tubes grown in vitro . The activity of β_glucanases was, in a certain extent, decreased by nojirimycin, an inhibitor of glucosidase. Pollen germination percentage reduced dramatically when nojirimycin was applied in the culture medium. In case that nojirimycin was added at 0 or 1 h after the onset of incubation, the inhibition rate was 99.6% and 91.4%, respectively. When 3 mmol/L of nojirimycin was applied in the liquid medium at 0, 1, 1.5 and 2 h after the onset of incubation, the growth of pollen tubes was interrupted, which resulted in the morphological change of the pollen tubes such as the newly grown portion of pollen tubes being bent, curved and swollen. Tracing the growth pattern of the individual pollen tube grown in semi_solid medium by video microscopy, the authors demonstrated that pollen tube growth rate was strongly inhibited by nojirimycin at concentrations ranged from 0.003 to 3 mmol/L. Moreover, the cytoplasmic arrangement and the morphology of the pollen tubes were also affected by nojirimycin. The growth inhibition brought about by nojirimycin was reversible. These results indicated that β_glucanases, which degrade 1,3_β_glucan and/or 1,4_β_glucan or 1,3:1,4_β_glucan constructed in the cell wall, are involved in pollen germination and pollen tube growth. It provides new insight into an understanding of the contribution of β_glucanases to the cell wall extensibility and the crucial role of cell wall in regards to the regulation of pollen tube growth.

促进猪生长的新探讨(二)

前生命期物(Probiotics) 前生命期物现巳广泛用以替代日粮中所使用的抗菌素物质。前生命期物在动物消化道内对微生物有着与抗菌素相反的作用。抗菌素在动物消化道内通过抑制和破坏细菌来控制微生物群体,用前生命期物实际是引入活的细菌于肠道内。

Enhanced Production of Hybrid Extracellular β-Glucanase by Re-combinant Escherichia coli Using Experimental Design Method

A genetically engineered Escherichia coli JM109 harboring pLF3 was used to produce a hybrid ex-tracellular β-glucanase. Starting with enzyme production medium, glycerol and yeast extract combined with NaNO3 were screened to be the most suitable carbon and nitrogen source, respectively. Analysis of six components of the enzyme production medium by employing statistical optimization methods such as Plackett-Burman design and steepest ascent showed that yeast extract was the only significant variable and its best concentration for enzyme production was 12g·L-1. After optimization of the medium, 297.71U·ml-1 of β-glucanase activity in the medium and 352350U·g-1 of β-glucanase selectivity could be obtained, which were 14 and 72 folds higher than those ob-tained from original medium, respectively. Even higher enzyme activities were achieved by batch cultivations in a conventional stirred bioreactor on the optimized medium.

Optimization of cultural conditions for thermostable β-1,3-1,4-glucanase production by Bacillus subtilis ZJF-1A5

The optimization of cultural conditions for β glucanase production by Bacillus subtilis ZJF 1A5 was investigated in flask trials. Temperature had great effect on β glucanase production which maximized at optimal temperature of 37℃ and decreased significantly when temperature was over 37℃.Charge quantity affected β glucanase production significantly. Adding oxygen vector N dodecane or acetic ether benefited β glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β glucanase production and the cultivation time span to reach the highest β glucanase activity. The optimal cultural conditions for β glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted by a second order polynomial model. The amount of β glucanase, α amylase and neutral protease produced by B subtilis ZJF 1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase.

Purification and some properties of a β-glucanase from a strain, Trichoderma reesei GXC

glucanase was purified from a solid\|state culture of \%Trichoderma reesei \%on wheat bran in three steps which comprised ammonium sulfate precipitation, Sephadex G\|100 chromatography, and DEAE\|Sephadex A\|50 chromatography. The molecular mass was determined to be 35.21 kilodaltons by sodium dodecyl sulfate\|12.5% polyacrylamide gel electrophoresis. The \%β\%\|glucanase at low pHs was more stable than that at high pHs, and optimum pH was 5.0. The optimum temperature was 60 ℃, and \%β\%\|glucanase was relatively stable at below 40 ℃ for 60 min. The \%K\%\-m of the enzyme on \%β\%\|glucan was 10.86 mg/ml, and the \%V\%\-\{max\} on \%β\%\|glucan was 14286 μmol of glucose equivalents per mg of the pure enzyme per min. The \%β\%\|glucanase activity was significantly inhibited by Fe\+\{3+\} ions, and was reduced in the presence of Cu\+\{2+\} ions, Mn\+\{2+\} ions and Mg\+\{2+\} ions at 5 mmol/L and 10 mmol/L, respectively. The \%β\%\|glucanase activity was stimulated by Co\+\{2+\} ions, Ca\+\{2+\} ions, Zn\+\{2+\} ions, and Fe\+\{2+\} ions at 1 mmol/L and 5 mmol/L, respectively.

Genetic mapping of quantitative trait loci associated with β-amylase and limit dextrinase activities and β-glucan and protein fraction contents in barley

High malting quality of barley （Hordeum vulgare L.） relies on many traits, such as β-amylase and limit dextrinase activities and β-glucan and protein fraction contents. In this study, interval mapping was utilized to detect quantitative trait loci （QTLs） affecting these malting quality parameters using a doubled haploid （DH） population from a cross of CM72 （six-rowed） by Gairdner （two-rowed） barley cultivars. A total of nine QTLs for eight traits were mapped to chromosomes 3H, 4H, 5H, and 7H. Five of the nine QTLs mapped to chromosome 3H, indicating a possible role ofloci on chromosome 3H on malting quality. The phenotypic variation accounted by individual QTL ranged from 8.08% to 30.25%. The loci of QTLs for D-glucan and limit dex- trinase were identified on chromosomes 4H and 5H, respectively. QTL for hordeins was coincident with the region of silica eluate （SE） protein on 3HS, while QTLs for albumins, globulins, and total protein exhibited overlapping. One locus on chromosome 3H was found to be related to （J-amylase, and two loci on chromosomes 5H and 7H were found to be associated with glutelins. The identification of these novel QTLs controlling malting quality may be useful for marker-assisted selection in improving barley malting quality.