title: Explorative multifactor approach for investigating global survival mechanisms of Campylobacter jejuni under environmental conditions.
abstract: 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.
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Norway. birgitte.moen@matforsk.no
authors.forename: Birgitte
authors.initials: B
authors.lastname: Moen
authors.forename: Astrid
authors.initials: A
authors.lastname: Oust
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Langsrud
authors.forename: Nick
authors.initials: N
authors.lastname: Dorrell
authors.forename: Gemma L
authors.initials: GL
authors.lastname: Marsden
authors.forename: Jason
authors.initials: J
authors.lastname: Hinds
authors.forename: Achim
authors.initials: A
authors.lastname: Kohler
authors.forename: Brendan W
authors.initials: BW
authors.lastname: Wren
authors.forename: Knut
authors.initials: K
authors.lastname: Rudi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016123:Campylobacter jejuni / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008954:Models, Biological; D015999:Multivariate Analysis; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010100:Oxygen / Q000494:pharmacology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; D010100:Oxygen