表达谷氨酸脱羧酶重组枯草芽孢杆菌的构建及其发酵条件的优化

谷氨酸脱羧酶（GAD）是生物合成γ-氨基丁酸（GABA）的关键酶,本研究通过基因工程构建了一株产GAD的重组枯草芽孢杆菌,并对其产GAD的发酵条件进行优化。分别通过单因素法、正交实验、极差分析和响应面法确定了最佳培养基成分（g/L）及发酵条件为:蔗糖23.5,豆粕10、乙酸铵为8.5、磷酸二氢钾4.1、七水硫酸镁0.5,p H7.0,培养温度37℃。在优化条件下GAD酶活达到0.413 U/m L,与优化前的GAD酶活0.143 U/m L相比,酶活提高了188.8%。本研究有助于后续开发枯草杆菌生产γ-氨基丁酸的工艺,以克服现在γ-氨基丁酸生产工艺中,大肠杆菌安全性的问题和乳酸菌成本过高的问题。      

MgO含量对CaO-SiO2-Al2O3-MgO熔渣中液态相影响的模拟

运用Factsage软件模拟了MgO含量对CaO-SiO₂-Al₂O₃-MgO熔渣中液相区的影响.结果表明,随着CaO-SiO₂-Al₂O₃-MgO渣中MgO含量增加,渣中低熔点液相区整体向低CaO高SiO₂区移动.相图中1500℃液相区比例由0%MgO（质量分数）时的25.05%上升至9%MgO（质量分数）时的52.69%,而后降至15%MgO时的46.70%.相图中1400℃液相区比例由3%MgO时的14.41%上升至11%MgO时的34.39%,而后降至15%MgO时的31.04%.相图中1300℃液相区比例由5%MgO时的5.57%上升至14%MgO时的11.02%,而后降至15%MgO时的10.50%.相图中1200℃液相区域比例在MgO为0~6%时为零,由7%MgO时的0.88%上升至11%MgO时的1.22%,在MgO为13%~15%时降为零.模拟结果可对以CaO-SiO₂-Al₂O₃-MgO为基本组元配置炼钢渣系的成分选择提供有效指导.     

植物乳杆菌LB-17产γ-氨基丁酸培养基优化

以植物乳杆菌（Lactobacillus plantarum Lb-17）为发酵菌株,以发酵产物γ-氨基丁酸产量为检测参数,对植物乳杆菌发酵产γ-氨基丁酸的发酵培养基进行优化。利用单因素实验和Box-Behnken响应曲面实验对发酵培养基进行优化得到最优培养基为:葡萄糖12.0 g/L、酵母粉18.0 g/L、Ca²⁺ 55.0 mmol/L、Mg²⁺ 60.0 mmol/L、L-谷氨酸钠26.0 g/L。优化后,植物乳杆菌Lb-17发酵γ-氨基丁酸产量达8.037 g/L,是优化前5.49 g/L提高1.5倍。      

γ-生育三烯酚的生物活性及其作用机理研究进展

维生素E包括生育酚和生育三烯酚两个亚族,每个亚族有四种单体（α,β,γ和δ）。相较于其他维生素E单体,γ-生育三烯酚（γ-T3）具有更好的抗肿瘤、神经保护、降低胆固醇、抗炎以及抑制脂肪产生的作用。本文旨在综述γ-T3的生物活性及其作用机理,提出目前γ-T3生物活性研究中存在的问题,并对其研究方向进行展望。      

浸泡水量对水豆豉理化特性的影响

基于浸泡水量不同的黄豆发酵的水豆豉来进行理化特性实验,随着浸泡水量的增加,pH增加,3倍浸泡量的水豆豉的蛋白质含量、酸度、氨基酸态氮、铵态氮和γ-谷氨酸转肽酶（GTP）含量都比其他浸泡水量的豆豉高,在感官评价上3倍浸泡量的水豆豉也优于其他浸泡量的水豆豉,3倍浸泡量的水豆豉的具有最好的理化品质。      

γ-氨基丁酸的制备方法与含量测定研究进展

γ-氨基丁酸（GABA）广泛存在于自然界中,具有保肝、利肾、健脑、延缓衰老等多种生理活性,应用于医药、保健食品、新资源食品和饲料添加剂等领域。本文对GABA的制备方法和含量检测方法进行了综述,为进一步研究提供参考。      

γ-辐照处理对谷物储藏及品质特性的影响研究进展

辐照作为一种低能耗、安全、有效的加工方式在食品工业上得到广泛应用。辐照对储藏谷物的主要作用包括:适宜剂量的辐照可杀害储粮中的害虫,且不会影响谷物品质;控制谷物中常见的致病菌,产毒菌素的生长,降解致病霉菌;通过作用于淀粉颗粒,提高谷物的营养品质和食用品质;另外,辐照还可延缓谷物老化,劣变的过程,提高保鲜期,提高谷物成品的生产效率。本文综述了辐照对谷物食品品质和营养的影响,分析评价了食品辐照的优劣及国际机构对辐照食品的认可进程,并对消费者的接受度等辐照领域的相关问题提出建议。      

A Study of Removing Chlorobenzene by the Synergistic Effect of Catalysts and Dielectric-Barrier Discharge Driven by Bipolar Pulse-Power

In this study, the improvement in the removal of chlorobenzene （C6H5Cl） in the air was investigated by combining dielectric barrier discharge （DBD） driven by bipolar pulse-power with catalysts. Molecular sieve 4A （MS-4A） and MnO2/γ-Al2O3 （MnO2/ALP） as two kinds of catalysts were tested at different positions in a DBD reactor. Catalysts were located either in the discharging area between two electrodes, or just behind the discharging area （in the afterglow area） closed to the outlet. The results indicated that DBD reactor with a bipolar pulse power-supply produced strong instant discharge and energetic particles, which can effectively activate catalysts of MS-4A and MnO2/ALP located in the afterglow area to achieve the synergistic effects on effective fission of chemical bonds of chlorobenzene. It was considered that the gas-chlorobenzene and the chlorobenzene adsorbed on the catalysts were decomposed simultaneously.     

High γ-aminobutyric acid production from lactic acid bacteria: Emphasis on Lactobacillus brevis as a functional dairy starter

γ-Aminobutyric acid (GABA) and GABA-rich foods have shown anti-hypertensive and anti-depressant activities as the major functions in humans and animals. Hence, high GABA-producing lactic acid bacteria (LAB) could be used as functional starters for manufacturing novel fermented dairy foods. Glutamic acid decarboxylases (GADs) from LAB are highly conserved at the species level based on the phylogenetic tree of GADs from LAB. Moreover, two functionally distinct GADs and one intact gad operon were observed in all the completely sequenced Lactobacillus brevis strains suggesting its common capability to synthesize GABA. Difficulties and strategies for the manufacture of GABA-rich fermented dairy foods have been discussed and proposed, respectively. In addition, a genetic survey on the sequenced LAB strains demonstrated the absence of cell envelope proteinases in the majority of LAB including Lb. brevis, which diminishes their cell viabilities in milk environments due to their non-proteolytic nature. Thus, several strategies have been proposed to overcome the non-proteolytic nature of Lb. brevis in order to produce GABA-rich dairy foods.     

米糠中产γ-氨基丁酸细菌分离及其接种发酵研究

利用薄层层析初步筛选出米糠中产γ-氨基丁酸（GABA）能力较强的菌株,对其16S rDNA序列进行分析,确定菌株种类;用氨基酸自动分析仪进一步筛选出高产GABA菌株;将高产GABA菌株接种到米糠进行发酵试验。结果表明,陈米糠更有利于分离到高产GABA菌株;筛选到产量较高的菌株16S rDNA序列分别与屎肠球菌（Enterococcus faecium）、棉子肠球菌（Enterococcus raffinosus）、大肠埃希氏菌（Escherichia coli）、短乳杆菌（Lactobacillus brevis）和宋内志贺杆菌（Shigella sonnei）相似性最高;接种单菌种发酵不能明显提高米糠中GABA含量,但混合接种地衣芽孢杆菌（Bacillus licheniformis）DY和乳酸菌L-44A可以使其含量达到184.6 mg/100 g（干质量）;利用蛋白酶处理米糠后接种乳酸菌L-44A可以使米糠中GABA含量达到245.8 mg/100 g（干质量）。