Explorative Multifactor Approach for Investigating Global Survival Mechanisms of Campylobacter jejuni under Environmental Conditions

• Published in: Applied and Environmental Microbiology 2005-04, Vol.71 (4), p.2086-2094
• Main Authors: Moen, Birgitte, Oust, Astrid, Langsrud, Øyvind, Dorrell, Nick, Marsden, Gemma L, Hinds, Jason, Kohler, Achim, Wren, Brendan W, Rudi, Knut
• Format: Article
• Language: English
• Subjects: aerobic conditions; anaerobic conditions; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriological methods and techniques used in bacteriology; Bacteriology; Biological and medical sciences; Campylobacter jejuni; Campylobacter jejuni - genetics; Campylobacter jejuni - growth & development; Campylobacter jejuni - metabolism; Culture Media; DNA, Bacterial - analysis; experimental design; Food contamination & poisoning; Food Microbiology; food pathogens; Fourier transform infrared spectroscopy; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial; microarray technology; Microbiology; Models, Biological; Multivariate Analysis; Oligonucleotide Array Sequence Analysis - methods; Oxygen - pharmacology; pathogen survival; Pathogens; Research methodology; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 23S - genetics; Spectroscopy, Fourier Transform Infrared; Survival analysis; Temperature
• ISSN: 0099-2240; 1098-5336
• 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°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°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.