| Bacterial Competition Assay Based on Extracellular D-amino Acid Production
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Author:
Date:
2018-04-05
[Abstract] Bacteria live in polymicrobial communities under tough competition. To persist in a specific niche many species produce toxic extracellular effectors as a strategy to interfere with the growth of nearby microbes. One of such effectors are the non-canonical D-amino acids. Here we describe a method to test the effect of D-amino acid production in fitness/survival of bacterial subpopulations within a community. Co-cultivation methods usually involve the growth of the competing bacteria in the same container. Therefore, within such mixed cultures the effect on growth caused by extracellular metabolites cannot be distinguished from direct physical interactions between species (e.g., T6SS effectors). However, this problem can be easily solved by using a filtration unit that allows free ...
[摘要] 在激烈的竞争中，细菌生活在多种微生物群落中。为了坚持特定的生态位，许多物种会产生有毒的细胞外效应物作为干扰附近微生物生长的策略。这种效应子之一是非规范的D-氨基酸。在这里我们描述一种方法来测试D-氨基酸生产对社区内细菌亚群的适应/存活的影响。共培养方法通常涉及相同容器中竞争细菌的生长。因此，在这种混合培养物中，细胞外代谢物对生长的影响不能与物种间的直接物理相互作用区分开（例如T6SS效应物）。然而，通过使用允许小分解代谢物（例如L-和D-氨基酸）自由扩散的过滤单元可以容易地解决这个问题，同时将不同亚群保持在独立区室中。
通过这种方法，我们已经证明D-精氨酸是由霍乱弧菌产生的杀菌剂效应物，其强烈影响不同微生物亚群的存活。此外，D-精氨酸可作为混合菌群中的一种协同工具，用于保护非生产成员免受竞争细菌的侵害。
【背景】细菌生活在多种多样的物种共存并争夺现有资源的多种微生物群落中。细菌设计为在特定生态位持续存在的许多策略之一是产生有毒的细胞外代谢物作为干扰其他微生物生长和/或生存力的策略。已知D-氨基酸长时间在细菌培养物中具有细胞形状和活力的强大作用（Bopp，1965; Fox等人，1944; Kobayashi等人， 1948年; Yaw和Kakavas，1952年; Lark和Lark，1959年; Grula，1960年; ...
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| Detection and Measurement of ROS in Tobacco Leaves
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Author:
Date:
2013-03-05
[Abstract] Leaf metabolism produces hydrogen peroxide (H2O2) at high rates, high level H2O2 accumulation can cause oxidative stress. This protocol describes a method for determining H2O2 concentration in tobacco leaves. In this method all extractions were performed with HClO4, neutralized, and pretreated with ascorbate oxidase to eliminate ascorbate interferences. H2O2 content was determined using a colorimetric assay spiked with an internal control. Interfering peroxides were determined in parallel using a negative control treated with catalase and subsequently subtracted.
[摘要] 叶代谢以高速率产生过氧化氢（H 2 O 2 O 2），高水平的H 2 O 2 O 2积累 可引起氧化应激。 该方案描述了用于测定烟草叶中H 2 O 2 O 2浓度的方法。 在该方法中，所有提取用HClO 4进行，中和，并用抗坏血酸氧化酶预处理以消除抗坏血酸盐干扰。 使用掺入内部对照的比色测定法测定H 2 O 2含量。 使用用过氧化氢酶处理的阴性对照平行测定干扰过氧化物，随后扣除。
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