Moen Birgitte, Oust Astrid, Langsrud Øyvind, Dorrell Nick, Marsden Gemma L, Hinds Jason, Kohler Achim, Wren Brendan W, Rudi Knut
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Norway.
Appl Environ Microbiol. 2005 Apr;71(4):2086-94. doi: 10.1128/AEM.71.4.2086-2094.2005.
Explorative approaches such as DNA microarray experiments are becoming increasingly important in microbial research. Despite these major technical advancements, approaches to study multifactor experiments are still lacking. We have addressed this problem by using rotation testing and a novel multivariate analysis of variance (MANOVA) approach (50-50 MANOVA) to investigate interacting experimental factors in a complex experimental design. Furthermore, a new rotation testing based method was introduced to calculate false-discovery rates for each response. This novel analytical concept was used to investigate global survival mechanisms in the environment of the major food-borne pathogen C. jejuni. We simulated nongrowth environmental conditions by investigating combinations of the factors temperature (5 and 25 degrees C) and oxygen tension (anaerobic, microaerobic, and aerobic). Data were generated with DNA microarrays for information about gene expression patterns and Fourier transform infrared (FT-IR) spectroscopy to study global macromolecular changes in the cell. Microarray analyses showed that most genes were either unchanged or down regulated compared to the reference (day 0) for the conditions tested and that the 25 degrees C anaerobic condition gave the most distinct expression pattern with the fewest genes expressed. The few up-regulated genes were generally stress related and/or related to the cell envelope. We found, using FT-IR spectroscopy, that the amount of polysaccharides and oligosaccharides increased under the nongrowth survival conditions. Potential mechanisms for survival could be to down regulate most functions to save energy and to produce polysaccharides and oligosaccharides for protection against harsh environments. Basic knowledge about the survival mechanisms is of fundamental importance in preventing transmission of this bacterium through the food chain.
诸如DNA微阵列实验之类的探索性方法在微生物研究中变得越来越重要。尽管取得了这些重大技术进步，但研究多因素实验的方法仍然不足。我们通过使用旋转测试和一种新颖的多变量方差分析（MANOVA）方法（50-50 MANOVA）来解决这个问题，以研究复杂实验设计中相互作用的实验因素。此外，还引入了一种基于旋转测试的新方法来计算每个反应的错误发现率。这种新颖的分析概念被用于研究主要食源性病原体空肠弯曲菌在环境中的全球生存机制。我们通过研究温度（5和25摄氏度）和氧张力（厌氧、微需氧和好氧）等因素的组合来模拟非生长环境条件。利用DNA微阵列生成有关基因表达模式的信息，并利用傅里叶变换红外（FT-IR）光谱来研究细胞中的整体大分子变化。微阵列分析表明，与测试条件下的参考（第0天）相比，大多数基因要么没有变化，要么下调，并且25摄氏度厌氧条件下的表达模式最为独特，表达的基因最少。少数上调的基因通常与应激相关和/或与细胞膜有关。我们利用FT-IR光谱发现，在非生长生存条件下，多糖和寡糖的含量增加。生存的潜在机制可能是下调大多数功能以节省能量，并产生多糖和寡糖以抵御恶劣环境。关于生存机制的基础知识对于防止这种细菌通过食物链传播至关重要。
