基于气相色谱-离子迁移谱法分析青霉侵染木耳菌丝的挥发性化合物

目的 基于气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry, GC-IMS)研究青霉侵染木耳菌丝的挥发性化合物, 发掘潜在的特征标志物。方法 以分离自木耳菌包的桔青霉、歧皱青霉及黑木耳菌丝为研究对象, 采用气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry, HS-GC-IMS)分析青霉侵染木耳菌丝不同时期挥发性化合物的种类及变化趋势, 并利用主成分分析(principal component analysis, PCA)比较不同侵染阶段挥发性化合物间的差异。结果 指纹图谱及PCA分析均可以比较明显地区分开青霉侵染木耳菌丝的不同阶段。挥发性化合物主要在桔青霉和歧皱青霉侵染木耳菌丝后的第4~8 d产生, 整体变化趋势基本一致, 共鉴定出41种化合物, 包括酯类、醇类、酮类、醛类及其他类。1-戊醇、乙酸己酯、2,3-戊二酮、2-丁酮、2,3丁二酮、1-丙醇、2-己醇、乙酸乙酯、丁酸乙酯、2-甲基丁酸等挥发性化合物可作为青霉侵染木耳菌丝的潜在标志物, 其中, 1-戊醇、乙酸己酯可作为青霉早期污染木耳菌丝的潜在标志物。3-羟基-2-丁酮可作为桔青霉侵染木耳菌丝后的潜在特征标志物。结论 本研究利用GC-IMS分析获得了两种青霉污染木耳菌丝的特征标志物, 为木耳栽培过程中青霉污染的早期预测提供了一定的理论基础。     

Factors affecting growth and pigmentation of Penicillium caseifulvum

Color formation, metabolite production and growth of Penicillium caseifulvum were studied in order to elucidate factors contributing to yellow discoloration of Blue Cheese caused by the mold. A screening experiment was set up to study the effect of pH, concentration of salt (NaCl), P, K, N, S, Mg and the trace metals Fe, Cu, Zn, Mn on yellow color formation, metabolite production and mold growth. Multivariate statistical analysis showed that the most important factor affecting yellow color formation was pH. The most pronounced formation of yellow color, supported by highest amount of colored metabolites, appeared at low pH (pH 4). Mold growth was not correlated to the yellow color formation. Salt concentration was the most important factor affecting mold growth and length of lag phase. Production of secondary metabolites was strongly influenced by both pH and salt concentration. The screening results were used to divide the metabolites into the following three groups: 1) correlated to growth, 2) correlated to color formation, and 3) formed at high pH. Subsequently, a full factorial experiment with factors P, Mg and Cu, showed that low P concentrations (2,000 mg/kg) induced yellow color formation. Among the factors contributing to yellow color formation, pH and salt concentration are easy to control for the cheesemaker, while the third factor, P-concentration, is not. Naturally occurring variations in the P-concentration in milk delivered to Blue Cheese plants, could be responsible for the yellow discoloration phenomenon observed in the dairy industry.     

Acidic β-mannanase from Penicillium pinophilum C1: Cloning, characterization and assessment of its potential for animal feed application

The β-mannanase gene, man5C1, was cloned from Penicillium pinophilum C1, a strain isolated from the acidic wastewater of a tin mine in Yunnan, China, and expressed in Pichia pastoris. The sequence analysis displayed the gene consists of a 1221-bp open reading frame encoding a protein of 406 amino acids (Man5C1). The deduced amino acid sequence of Man5C1 showed the highest homology of 57.8% (identity) with a characterized β-mannanase from Aspergillus aculeatus belonging to glycoside hydrolase family 5. The purified rMan5C1 had a high specific activity of 1035 U mg^–1 towards locust bean gum (LBG) and showed highest activity at pH 4.0 and 70°C. rMan5C1 was adaptable to a wide range of acidity, retaining > 60% of its maximum activity at pH 3.0–7.0. The enzyme was stable over a broad pH range (3.0 to 10.0) and exhibited good thermostability at 50°C. The K_m and V_max values were 5.6 and 4.8 mg mL^–1, and 2785 and 1608 μmol min^–1 mg^–1, respectively, when LBG and konjac flour were used as substrates. The enzyme had strong resistance to most metal ions and proteases (pepsin and trypsin), and released 8.96 mg g^–1 reducing sugars from LBG in the simulated gastric fluid. All these favorable properties make rMan5C1 a promising candidate for use in animal feed.     

洗涤剂用酶的研究与开发──新型碱性脂肪酶

讨论了碱性脂肪酶的性质、生产及其在洗涤剂中的应用     

Fungal Bioleaching of Metals From Mine Tailing

The present study was undertaken to develop an economically feasible and environmental-friendly technique to recover metals (Ni, Cu, Co, Zn, Mg) from mine tailing by employing Penicillium chrysogenum strain KBS3. The potential of Penicillium chrysogenum in generating a variety of organic acids was studied and the effect of different organic wastes as substrates was evaluated. Maximum solubilization of nickel (55%), copper (67%), magnesium (69%), cobalt (60%), and zinc (65%) was achieved in the media containing glucose, tea leaves, molasses, and waste winery grapes as substrates.     

棒曲霉素的生物合成、调控机制及其控制技术研究进展

棒曲霉素(patulin)是一种真菌的次生代谢产物。它对人和动物具有急性和慢性毒性,是污染水果及其加工制品的最重要的真菌毒素之一。食品中的棒曲霉素污染是一个全球性的问题,受到世界各国的关注,100多个国家和地区对果汁等水果加工制品中棒曲霉素的最高含量做了限定。棒曲霉素主要由青霉属、曲霉属、拟青霉属和丝衣霉属中的部分真菌产生。其中,扩展青霉(Penicillium expansum)是生产上棒曲霉素最重要的产生菌,因此成为研究棒曲霉素生物合成和调控机制的模式材料。近年来,随着食品安全问题越来越被人们重视,水果及其加工制品的真菌毒素污染问题也受到越来越多的关注,相关领域的研究逐渐成为热点。本文主要阐述了棒曲霉素的生物合成途径、分子基础、内外源调控因子和分子调控机制以及控制技术等方面的最新研究进展,并展望了棒曲霉素相关研究未来的重点。     

圆弧青霉PG37碱性脂肪酶的发酵工艺条件

研究了圆弧青霉PG3 7碱性脂肪酶的发酵工艺条件 ,优化了PG3 7的摇瓶最适产酶条件 .其中 ,发酵培养基的组成为 (g/dL) :豆饼粉 3 .0 ,玉米浆 3 .0 ,磷酸氢二钾 1 .0 ,硫酸镁 0 .1 ,大豆磷脂0 .5,柠檬酸钠 0 .0 5,花生油 0 .2 ;发酵培养基起始 pH 7.5,发酵温度 (2 9± 1 )℃ ,摇床转速 2 50r/min ,发酵周期 96h ,发酵期间于 3 6,54,72h分别流加 0 .4 g/dL花生油 .在此条件下 ,PG3 7的脂肪酶产率为 2 0 60 μmol/ (min·mL) .PG3 7在 2 5L的实验室小罐中的产酶水平为 1 90 0 μmol/ (min·mL) .     

Patulin in apple juices: Incidence and likely intake in an Indian population

The quality and safety of Ayurvedic formulations has become a serious issue, as this Indian system of medicine is used by 80% of the Indian population. Hence, the present study was performed to evaluate heavy metals contents by flame atomic absorbance spectroscopy (AAS) measurements and confirmation by inductive coupled plasma–mass spectroscopy (ICP-MS). A total of 78 formulations (56 herbal, 19 herbometallic and 3 metallic) were sampled. In herbal formulations, lead in 19.6% (11/56), cadmium in 21.4% (12/56), mercury and arsenic in 5.3% (3/56) were above the limit. Lead in 52.6% (10/19) of samples, cadmium in 26.3% (5/19) and mercury and arsenic contained in one herbometallic sample was above the limit. Heavy metals in all metal formulations were above the WHO limit. Significant batch variation was observed. The analytical results of flame AAS and ICP-MS did not differ significantly in the range of measurements in this study, which proves that both methods are satisfactory for estimation of heavy metals in these type of samples.