Genomic and metabolomic analysis of Bacillus licheniformis with enhanced poly-γ-glutamic acid production through atmospheric and room temperature plasma mutagenesis

Poly-γ-glutamic acid is an extracellular polymeric substance with various applications owing to its valuable properties of biodegradability, flocculating activity, water solubility, and nontoxicity. However, the ability of natural strains to produce poly-γ-glutamic acid is low. Atmospheric and room temperature plasma was applied in this study to conduct mutation breeding of Bacillus licheniformis CGMCC 2876, and a mutant strain M32 with an 11% increase in poly-γ-glutamic acid was obtained. Genome resequencing analysis identified 7 nonsynonymous mutations of ppsC encoding lipopeptide synthetase associated with poly-γ-glutamic acid metabolic pathways. From molecular docking, more binding sites and higher binding energy were speculated between the mutated plipastatin synthase subunit C and glutamate, which might contribute to the higher poly-γ-glutamic acid production. Moreover, the metabolic mechanism analysis revealed that the upregulated amino acids of M32 provided substrates for glutamate and promoted the conversion between L- and D-glutamate acids. In addition, the glycolytic pathway is enhanced, leading to a better capacity for using glucose. The maximum poly-γ-glutamic acid yield of 14.08 g·L^–1 was finally reached with 30 g·L^–1 glutamate.     

Comparative Cytotoxicity of Artemisinin and Cisplatin and Their Interactions with Chlorogenic Acids in MCF7 Breast Cancer Cells

In parts of Africa and Asia, self‐medication with a hot water infusion of Artemisia annua (Artemisia tea) is a common practice for a number of ailments including malaria and cancer. In our earlier work, such an extract showed better potency than artemisinin alone against both chloroquine‐sensitive and ‐resistant parasites. In this study, in vitro tests of the infusion in MCF7 cells showed high IC₅₀ values (>200 μM ). The combination of artemisinin and 3‐caffeoylquinic acid (3CA), two major components in the extract, was strongly antagonistic and gave a near total loss of cytotoxicity for artemisinin. We observed that the interaction of 3CAs with another cytotoxic compound, cisplatin, showed potentiation of activity by 2.5‐fold. The chelation of cellular iron by 3CA is hypothesized as a possible explanation for the loss of artemisinin activity.     

化学清洗液的游离柠檬酸浓度测定方法的改进

依据DL/T 794—2012所述方法重新制作了p H-Fa表,并以已知浓度的模拟柠檬酸清洗液验证了使用新旧p H-Fa表时测定结果的准确性。     

核桃壳活性炭的制备及其对烟酸缓释性能的研究

以二氧化碳(CO2)物理活化法制备了核桃壳活性炭,考察了活化温度、活化时间对核桃壳活性炭得率及烟酸吸附量的影响。以所制备的核桃壳活性炭为烟酸载体,在不同的释放介质(蒸馏水、人工胃液或人工肠液)中进行烟酸释放性能研究。结果表明,人工胃液和人工肠液能促进活性炭对烟酸的释放,其累计释放率分别达到43.96%和47.69%。核桃壳活性炭在3种不同介质中的不同释放阶段的释放过程均符合Higuchi模型。     

Preparation of Lung-Targeting,Emodin-Loaded Polylactic Acid Microspheres and Their Properties

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) has been identified to have the potential to improve lung fibrosis and lung cancer. To avoid the liver and kidney toxicities and the fast metabolism of emodin, emodin-loaded polylactic acid microspheres (ED-PLA-MS) were prepared and their characteristics were studied. ED-PLA-MS were prepared by the organic phase dispersion-solvent diffusion method. By applying an orthogonal design, our results indicated that the optimal formulation was 12 mg/mL PLA, 0.5% gelatin, and an organic phase:glycerol ratio of 1:20. Using the optimal experimental conditions, the drug loading and encapsulation efficiencies were (19.0 ± 1.8)% and (62.2 ± 2.6)%, respectively. The average particle size was 9.7 ± 0.7 μm. In vitro studies indicated that the ED-PLA-MS demonstrated a well-sustained release efficacy. The microspheres delivered emodin, primarily to the lungs of mice, upon intravenous injection. It was also detected by microscopy that partial lung inflammation was observed in lung tissues and no pathological changes were found in other tissues of the ED-PLA-MS-treated animals. These results suggested that ED-PLA-MS are of potential value in treating lung diseases in animals.     

溶剂法合成2-羟基-1-萘甲酸的工艺研究

以β-萘酚和氢氧化钠为原料,正辛烷为溶剂,合成了2-羟基-1-萘甲酸,纯度达98%以上。通过正交实验研究了反应压力、反应温度和反应时间对收率的影响,确定了优化的工艺条件:反应压力0.8 MPa,反应温度90℃,反应时间8 h,该条件下收率达82.83%。     

酶解奶油增香物制备工艺及其在奶香饲料调味剂中的应用

以开发具有发酵乳脂味、并伴有一定奶油香的天然奶味香精为目的,筛选酶品种和酶解底物,研究酶解时间、酶解温度、pH、酶添加量、底物浓度对乳脂酶酶解无水奶油制备天然奶味香精的影响。以感官评分作为主要评定指标,酸价作为参考,在单因素实验的基础上,采用正交实验分析与优化。结果表明：在酶解时间6 h、酶解温度50 ℃、pH6、乳脂肪酶添加量2.5%、底物质量分数85%条件下所得的奶味香精,具有较浓郁的发酵乳脂味和一定的奶油香气,香气柔和、协调性较好。     

咖啡酸衍生物对自由基致DNA氧化损伤的联合保护作用

目的:探讨咖啡酸衍生物（CADs）:绿原酸（Chlorogenic acid,ChA）、阿魏酸（Ferulic acid,FeA）、迷迭香酸（Rosmarinic acid,RoA）对自由基致DNA损伤的联合抑制保护效果。方法:运用DPPH自由基及羟自由基反应模型观察不同组成的CADs对自由基的淬灭效应,以CuSO₄-Phen-VitC-H₂O₂-DNA化学发光体系测定不同成分的多酚类物质对·OH致DNA损伤的抑制作用。结果:在30min时间内,三种CADs联合组在浓度为25、50、100、200μg/mL时,对DPPH·清除率分别为28.93%、58.39%、83.93%和84.09%;对·OH清除率分别为33.43%、55.27%、71.23%、77.49%。在DNA化学发光体系中,在25～200μg/mL范围内,三种CADs联合组对DNA损伤产物发光抑制率为12.49%～81.09%。结论:CADs能有效清除DPPH自由基和羟自由基,抑制羟自由基引发的DNA损伤程度,并延迟其受损伤的时间。在各实验组中三种CADs联用组在对DPPH自由基清除率、DNA损伤产物发光抑制率以及保护DNA损伤的能力均最强,体现出协同作用。