Effect of environmental stress factors on the uptake and survival of Campylobacter jejuni in Acanthamoeba castellanii

BMC Microbiology

Research Article

Anders Wolff¹  Klaus Qvortrup²  Carole Creuzenet³  Xuan Thanh Bui⁴  Dang Duong Bang⁵ 

[1] BioLabChip group, Department of Micro and Nanotechnology, Technical University of Denmark, DK-2800, Kgs Lyngby, Denmark;Department of Biomedical Sciences, University of Copenhagen, 2200, Copenhagen N, Denmark;Department of Microbiology and Immunology, Infectious Diseases Research Group, University of Western Ontario, N6A 5C1, London, ON, Canada;National Veterinary Institute, Technical University of Denmark, DK-8200, Aarhus N, Denmark;Department of Microbiology and Immunology, Infectious Diseases Research Group, University of Western Ontario, N6A 5C1, London, ON, Canada;National Veterinary Institute, Technical University of Denmark, DK-8200, Aarhus N, Denmark;Laboratory of Applied Micro and Nanotechnology, National Food Institute, Technical University of Denmark, DK-2860, Søborg, Denmark;

关键词: Campylobacter jejuni;    Acanthamoeba castellanii;    Environmental stresses;    Virulence;   

DOI  :  10.1186/1471-2180-12-232

 received in 2012-05-03, accepted in 2012-10-03,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundCampylobacter jejuni is a major cause of bacterial food-borne illness in Europe and North America. The mechanisms allowing survival in the environment and transmission to new hosts are not well understood. Environmental free-living protozoa may facilitate both processes. Pre-exposure to heat, starvation, oxidative or osmotic stresses encountered in the environment may affect the subsequent interaction of C. jejuni with free-living protozoa. To test this hypothesis, we examined the impact of environmental stress on expression of virulence-associated genes (ciaB, dnaJ, and htrA) of C. jejuni and on its uptake by and intracellular survival within Acanthamoeba castellanii.ResultsHeat, starvation and osmotic stress reduced the survival of C. jejuni significantly, whereas oxidative stress had no effect. Quantitative RT-PCR experiments showed that the transcription of virulence genes was slightly up-regulated under heat and oxidative stresses but down-regulated under starvation and osmotic stresses, the htrA gene showing the largest down-regulation in response to osmotic stress. Pre-exposure of bacteria to low nutrient or osmotic stress reduced bacterial uptake by amoeba, but no effect of heat or oxidative stress was observed. Finally, C. jejuni rapidly lost viability within amoeba cells and pre-exposure to oxidative stress had no significant effect on intracellular survival. However, the numbers of intracellular bacteria recovered 5 h post-gentamicin treatment were lower with starved, heat treated or osmotically stressed bacteria than with control bacteria. Also, while ~1.5 × 103 colony forming unit/ml internalized bacteria could typically be recovered 24 h post-gentamicin treatment with control bacteria, no starved, heat treated or osmotically stressed bacteria could be recovered at this time point. Overall, pre-exposure of C. jejuni to environmental stresses did not promote intracellular survival in A. castellanii.ConclusionsTogether, these findings suggest that the stress response in C. jejuni and its interaction with A. castellanii are complex and multifactorial, but that pre-exposure to various stresses does not prime C. jejuni for survival within A. castellanii.

【 授权许可】

Unknown   
© Bui et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.