Silver uptake byAgaricus bisporus from an artificially enriched substrate

The champignon mushroomAgaricus bisporus was cultivated on compost (wheat and rye straw, hens' manure, gypsum, urea and peat) artificially fortified with silver nitrate added at four different concentrations (0.01, 0.1, 1.0 and 10.3 mg/kg) and 0 mg/kg (control) on a dry weight basis. The method of measurement was flame atomic absorption spectrophotometry after dry ashing of the samples at 420° C and dissolving the residue in 1M nitric acid. The highest concentration of silver, reaching between 120±30–150±36 mg/kg on a dry weight basis, was observed in fruit bodies grown on the most contaminated substrate containing 10.3 mg added Ag/kg dry weight. The silver concentration in caps/stalks/whole fruit bodies ofA. bisporus was positively correlated (r=0.72; P<0.001) with an increasing level of fortification of the substrate. The bioconcentration factor (BCF) of silver in caps/stalks/whole fruit bodies ofA. bisporus was inversely correlated (–0.44bisporus.

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Silberaufnahme von Champignons (Agaricus bisporus) aus künstlich angereichertem Substrat

Zusammenfassung Champignons (Agaricus bisporus) wurden auf Kompost (Weizen- und Roggenstroh, Hühnerdung, Gips, Harnstoff und Torf) gezüchtet, welcher künstlich mit Silbernitrat in vier verschiedenen Mengen-0 (Kontrolle), 0,01, 0,1, 1,0 und 10,3 mg/kg-Trockenmasse angereichert wurde. Als Meßmethode wurde die Flammen AAS verwendet nach dem trockenen Veraschen der Proben bei 420 °C und Auflösen des Rückstandes in 1 M Salpetersäure.Die größte Silberkonzentration von 12±4–14±3 mg/kg Feuchtmasse und 120±30–150±36 mg/kg Trockenmasse wurde in den Fruchtkörpern festgestellt, die auf einem 10,3 mg Ag/kg Trockenmasse enthaltendem Substrat gewachsen sind. Die Silberkonzentration in allen Teilen des Fruchtkörpers hat positiv (r=0,72; p<0,001) mit steigendem Niveau der Substratanreicherung korreliert. Der Biokonzentrationskoeffizient (BCF) von Silber in den Pilzhüten, Strünken und ganzen Fruchtkörpern zeigte eine negative Korrelation (–0,44     

Heavy metal bioaccumulation by cultivated Agaricus bisporus from artificially enriched substrates

 Cultivated Agaricus bisporus possess the ability to bioaccumulate seven heavy metals (Pb, Cd, Hg, Fe, Cu, Mn, and Zn). The cultivated champignon mushroom A. bisporus was grown in soil composts of 16 different compositions. An edible mushroom, A. bisporus was also cultivated on humic compost artificially fortified with the seven heavy metals at five different concentrations (0.1 mg/kg, 0.5 mg/kg, 1.0 mg/kg, 3.0 mg/kg, and 10.0 mg/kg) and on control substrate (0 mg/kg) on a dry weight basis. The method of measuring bioaccumulation was flame atomic absorption spectrophotometry. Received: 1 October 1997 / Revised version: 19 January 1998     

Heavy metal bioaccumulation by cultivated Agaricus bisporus from artificially enriched substrates

Cultivated Agaricus bisporus possess the ability to bioaccumulate seven heavy metals (Pb, Cd, Hg, Fe, Cu, Mn, and Zn). The cultivated champignon mushroom A. bisporus was grown in soil composts of 16 different compositions. An edible mushroom, A. bisporus was also cultivated on humic compost artificially fortified with the seven heavy metals at five different concentrations (0.1 mg/kg, 0.5 mg/kg, 1.0 mg/kg, 3.0 mg/kg, and 10.0 mg/kg) and on control substrate (0 mg/kg) on a dry weight basis. The method of measuring bioaccumulation was flame atomic absorption spectrophotometry.     

Evaluation of harvested mushrooms and viability of Agaricus bisporus growth using casing materials made from spent mushroom substrate

The present work evaluates of harvested mushroom and viability of Agaricus bisporus growth in several casing materials based on spent mushroom substrate. The experiment consisted of eight casing layer, which six were made with spent mushroom substrate. The results confirm the usefulness of reincorporating the spent substrate in new cultivation cycles as an ingredient of casing mixtures. In general, biological efficiency was high, three of the SMS based‐casings surpassing the threshold value of 100 kg 100 kg^?1 of compost. The high electrical conductivity of mixtures containing a large proportion of spent substrate limits the extent to which it can be used, although mixing it with other materials (such as peat) reduces these values to acceptable levels. In short, it makes economic and environmental sense to reuse spent mushroom substrate as an ingredient of alternative casing materials.     

Temporal variations and controlling factors of nitrogen export from an artificially drained coastal forest

Nitrogen losses in drainage water from coastal forest plantations can constrain the long term sustainability of the system and could negatively affect adjacent nutrient sensitive coastal waters. Based on long-term (21 years) field measurements of hydrology and water quality, we investigated the temporal variations and controlling factors of nitrate and dissolved organic nitrogen (DON) export from an artificially drained coastal forest over various time scales (interannual, seasonal, and storm events). According to results of stepwise multiple linear regression analyses, the observed large interannual variations of nitrate flux and concentration from the drained forest were significantly (p < 0.004) controlled by annual mean water table depth, and annual drainage or precipitation. Annual precipitation and drainage were found to be dominant factors controlling variations of annual DON fluxes. Temporal trends of annual mean DON concentration could not be explained explicitly by climate or hydrologic factors. No significant difference was observed between nitrogen (both nitrate and DON) export during growing and nongrowing seasons. Nitrate exhibited distinguished export patterns during six selected storm events. Peak nitrate concentrations during storm events were significantly (p < 0.003) related to 30-day antecedent precipitation index and the minimum water table depth during individual events. The temporal variations of DON export within storm events did not follow a clear trend and its peak concentration during the storm events was found to be significantly (p < 0.006) controlled by the short-term drying and rewetting cycles.     

双孢蘑菇中核酸提取的研究

通过对酶解法、热回流法、超声波和微波法提取双孢蘑菇中核酸效果进行了比较,结果表明微波法优于其它方法。最终,确立采用微波破壁提取双孢蘑菇中核酸。经单因素(时间、功率、NaCl%、pH)实验和正交实验,得最佳提取条件为:30min、300W、4%NaCl、pH为11。用定磷法测得双孢蘑菇核酸提取率为2.78%。     

双孢蘑菇来源非特异性过氧合酶在 毕赤酵母中的表达及生化表征

本研究以来源于(Agaricus bisporus var. bisporus,Abvb)的非特异性过氧合酶AbvbUPO为目标蛋白,实现了其在毕赤酵母GS115中的异源分泌表达。Westernblot检测结果表明重组AbvbUPO分子量为35ku。酶生化表征研究发现,非特异性过氧合酶AbvbUPO的最适反应温度和pH分别为35℃和3.0。通过过氧化氢耐受性实验,发现2 mM以上的过氧化氢会导致AbvbUPO钝化。为保持AbvbUPO在反应过程中的活力,原位生成过氧化氢的AbvbUPO酶级联催化反应被应用于其催化能力的鉴定。以乙基苯为底物的AbvbUPO酶级联催化反应,经过4h的反应后,产物β-苯乙醇的得率可达14.40%。上述研究表明,AbvbUPO是一种不耐受高温和高浓度过氧化氢的中温酶,但在原位生成过氧化氢的级联反应中AbvbUPO可保持良好的催化性能。本研究为非特异性过氧合酶的异源表达和生物催化应用提供了一个良好的借鉴。     

Bactericidal effects of negative air ions on airborne and surface Salmonella enteritidis from an artificially generated aerosol

The bactericidal effect of high levels of negative ions was studied using a custom-built electrostatic space charge device. To investigate whether the ion-enriched air exerted a bactericidal effect, an aerosol containing Salmonella Enteritidis (SE) was pumped into a sealed plastic chamber. Plates of XLT4 agar were attached to the walls, top, and bottom of the chamber and exposed to the aerosol for 3 h with and without the ionizer treatment. The plates were then removed from the chamber, incubated at 37 degrees C for 24 h, and colonies were counted. An average of greater than 10(3) CFU/plate were observed on plates exposed to the aerosol without the ionizer treatment (control) compared with an average of less than 53 CFU/plate on the ionizer-treated plates. In another series of experiments, the SE aerosol was pumped for 3 h into an empty chamber containing only the ionizer and allowed to collect on the internal surfaces. The inside surfaces of the chamber were then rinsed with 100 ml phosphate-buffered saline that was then plated onto XLT4 plates. While the rinse from the control chamber contained colony counts greater than 400 CFU/ml of wash, no colonies were found in the rinse from the ionizer-treatment chamber. These results indicate that high levels of negative air ions can have a significant impact on the airborne microbial load, and that most of this effect is through direct killing of the organisms. This technology, which also causes significant reduction in airborne dust, has already been successfully applied for poultry hatching cabinets and caged layer rooms. Other potential applications include any enclosed space such as food processing areas, medical institutions, the workplace, and the home, where reduction of airborne and surface pathogens is desired.     

Migration of Antimicrobial Silver from Composites of Polylactide with Silver Zeolites

ABSTRACT: Silver ion migration and antimicrobial activity of PLA (polylactic acid-polylactide)/silver zeolite composites were investigated. Films prepared by solution-casting/solvent evaporation, or by melt-mixing/compression molding were compared. Silver migration to food simulants and TSB (tryptone soy broth) was quantified at different temperatures. Antimicrobial activity against Staphylococcus aureus and Escherichia coli was measured following the Japanese Industrial Standard JIS Z 2801. All types of PLA/silver zeolite composites released Ag⁺ ions. A more intense ionic exchange with the zeolites and a significant, but low, antimicrobial activity in solution were found in cast films. To attain antimicrobial effects, however, migrated ions ought to be in the range of the legal limit of 0.05 mg Ag⁺/kg food stated by the European Food Safety Agency (EFSA). Silver migration and antimicrobial activity were sensitive to the methodology chosen to process the PLA films, the ionic strength of the medium, and the ion motility in the polymer matrix. Practical Application: Silver exchanged zeolites incorporated in food contact polymers are gaining importance as antimicrobial agents. Migration of silver ions from polymer matrices, however, is legally restricted. Therefore a compromise between silver migration and antimicrobial activity needs to be critically analyzed to validate novel materials in food packaging applications.     

双孢菇边角料制备ACE抑制肽

以工厂生产的双孢菇菇柄、异形菇等边角料为原料,利用碱溶酸沉法提取双孢菇蛋白,超声波处理后,分别选用胰蛋白酶、碱性蛋白酶和复合蛋白酶对其进行酶解,通过测定蛋白水解度和ACE抑制率确定最佳的蛋白酶种类。采用响应面设计方法,优化蛋白酶酶解工艺条件,以期获得更高ACE抑制率的活性肽。结果表明,碱性蛋白酶酶解双孢菇蛋白产生的ACE抑制率最大,其最优酶解工艺参数为:碱性蛋白酶添加量6.25 mg/100 m L,酶解温度40.47℃,酶解时间92.97 min,酶解pH值8.04,此时ACE抑制率可达43.75%,在该条件下的验证试验测得水解液的ACE抑制率为43.4%,与预测值相近。经真空冷冻干燥,制得具有抑制ACE活性的肽样品,得率为24.36 mg/g,工业化生产前景良好,可为双孢菇产业边角料高值利用提供新途径。     

双孢菇废弃物菇柄多糖提取工艺研究

为扩大双孢菇废弃物菇柄的利用,以水为浸提溶剂,通过单因素实验研究了浸提温度、浸提时间、液固比、提取次数、乙醇用量和醇析时间对双孢菇废弃物菇柄多糖得率的影响,并采用正交实验对提取工艺进行优化。结果表明,多糖得率的主要影响因素及顺序为提取次数、浸提时间、浸提温度、液固比;在乙醇用量为2倍体积,醇析时间为2h时,最佳提取工艺参数为浸提温度85℃、浸提时间90min、液固比为15∶1、提取次数为3次,此时多糖得率为5.50%。      

超声波复合酶法提取双孢菇多糖的研究

采用超声波辅助复合酶提法提取双孢菇粗多糖。实验中利用单因素实验探索并确定了超声波的最佳提取时间和料液比分别为30min,1:20。对于复合酶的反应条件,采取L9(34)正交试验确定纤维素酶和中性蛋白酶的最佳工艺条件分别为:纤维素酶加酶量480u/g,pH4.0,酶解温度50℃,酶解时间100min;中性蛋白酶的加酶量100u/g,pH7.5,酶解温度45℃,酶解时间100min。实验中采用超声波辅助破壁方法,提高了纤维素酶的破壁效率,提高了双孢菇多糖的提取率。     

褐蘑菇水溶性多糖分级组分的抗氧化性能

采用水提醇沉法提取并精制褐蘑菇多糖(WPPA),用体积分数60%、70%和80%乙醇分级醇沉分离得3种粗多糖WPPA60、WPPA70和WPPA80;通过还原力、清除超氧阴离子自由基(O-2.)、清除羟自由基(.OH)和抑制H2O2诱导红细胞氧化溶血实验评价3种褐蘑菇多糖体外抗氧化能力。结果表明:WPPA60、WPPA70和WPPA80具有较强的还原能力,对O-2.和.OH具有较强的清除作用;对H2O2诱导红细胞氧化溶血及MDA生成有很强的抑制作用;抗氧化能力从强到弱依次是WPPA70>WPPA80>WPPA60。     

双孢菇水提物抗疲劳作用研究

目的:探讨双孢菇水提物对小鼠的抗疲劳效果。方法:将新鲜双孢菇烘干、粉碎、过筛得双孢菇干粉,按一定比例水浴提取,过滤后滤液为受试样品。受试样品分别以高、中、低三个剂量给小鼠灌胃,对照组灌胃蒸馏水,连续灌胃15d后,小鼠负重5%体重的铅皮,在温度为(30±1)℃的水箱中游泳造成疲劳。拨眼球取血,并取内脏,进行血乳酸、血清尿素氮和肝糖原含量的测定。结果:双孢菇水提物能延长小鼠负重游泳时间,降低小鼠运动后血清尿素氮和血乳酸水平,提高肝糖原的储备量。结论:双孢菇水提物具有明显的抗疲劳功效。     

双孢菇废弃菇柄核酸超声提取工艺优化

为了提高核酸得率,增加双孢菇废弃菇柄的经济价值。本文以双孢菇废弃菇柄为原料,通过单因素试验研究了超声功率、超声工作/间歇时间、超声时间、液固比对核酸提取的影响,并采用响应面法对核酸超声提取工艺进行优化。结果表明,在单因素试验结果基础上,再采用响应面分析法对主要工艺参数进行优化,得到双孢菇废弃菇柄中核酸提取最优工艺参数为:超声功率580 W,液固比34∶1 m L/g,超声时间15 min,理论核酸得率3.49 g/100 g。通过验证试验,实际核酸得率可达3.43 g/100 g,实验证明模型拟合程度良好,误差较小。与传统工艺相比,超声波提取核酸不仅快速高效,且反应过程无物料损失和无副反应发生,是一种安全、经济和简便的提取方法。     

双孢菇漆酶的固定化及其对邻苯二甲酸二甲酯降解的研究

为提高漆酶的利用效率,进一步开发其在环境治理中的应用,以海藻酸钠为载体,采用单因素实验对双孢菇漆酶凝胶包埋固定化的工艺进行探讨,并利用固定化漆酶对邻苯二甲酸二甲酯（DMP）进行降解实验。结果表明,采用直接包埋方式,固定化最佳单因素条件为:给酶量160 U/g载体,海藻酸钠浓度为3%,CaCl₂浓度为0.15 mol/L,固定化时间为2 h,可以获得较佳的固定化效果。利用固定化漆酶降解DMP时,降解率随DMP初始浓度的增加而下降,在pH3、4.5对DMP具有较好的降解效果,在25 mg/L的DMP溶液（pH4.5）中添加小分子介质ABTS浓度达到0.3 mmol/L,投加2 U/g固定化小球反应24 h,降解率最高达到56.9%。研究结果为处理含DMP污染提供了一种有效的方法和理论基础。      

双孢蘑菇源抗氧化肽的美拉德反应修饰研究

以还原力为指标对双孢蘑菇源抗氧化肽进行美拉德反应修饰研究。通过单因素实验研究了糖种类、体积比、pH、时间对双孢蘑菇源抗氧化肽美拉德反应修饰的影响,在此基础上采用正交实验优化了双孢蘑菇源抗氧化肽的美拉德反应修饰工艺。实验结果表明双孢蘑菇源抗氧化肽的最佳美拉德反应修饰工艺为:以果糖作为修饰反应物,果糖、双孢蘑菇源抗氧化肽二者的体积比为4:1,pH11.0,时间150min;该条件下制备的美拉德反应产物的还原力大约是修饰前的5倍,提示美拉德反应是提高抗氧化肽抗氧化活性的有效方法。      

Importance of an N-terminal extension in ribonuclease HII from Bacillus stearothermophilus for substrate binding

The gene encoding ribonuclease HII from Bacillus stearothermophilus was cloned and expressed in Escherichia coli. The overproduced protein, Bst-RNase HII, was purified and biochemically characterized. Bst-RNase HII, which consists of 259 amino acid residues, showed the highest amino acid sequence identity (50.2%) to Bacillus subtilis RNase HII. Like B. subtilis RNase HII, it exhibited Mn2+-dependent RNase H activity. It was, however, more thermostable than B. subtilis RNase HII. When the Bst-RNase HII amino acid sequence is compared with that of Thermococcus kodakaraensis RNase HII, to which it shows 29.8% identity, 30 residues are observed to be truncated from the C-terminus and there is an extension of 71 residues at the N-terminus. The C-terminal truncation results in the loss of the alpha9 helix, which is rich in basic amino acid residues and is therefore important for substrate binding. A truncated protein, Delta59-Bst-RNase HII, in which most of the N-terminal extension was removed, completely lost its RNase H activity. Surface plasmon resonance analysis indicated that this truncated protein did not bind to the substrate. These results suggest that the N-terminal extension of Bst-RNase HII is important for substrate binding. Because B. subtilis RNase HII has an N-terminal extension of the same length and these extensions contain a region in which basic amino acid residues are clustered, the Bacillus enzymes may represent a novel type of RNase H which possesses a substrate-binding domain at the N-terminus.