Isolation and analysis of differentially expressed genes in Penicillium glabrum subjected to thermal stress

This is an author manuscript that has been accepted for publication in Journal of Medical Microbiology, copyright Society for General Microbiology, but has not been copy-edited, formatted or proofed. Cite this article as appearing in Journal of Medical Microbiology. This version of the manuscript may not be duplicated or reproduced, other than for personal use or within the rule of 'Fair Use of Copyrighted Materials' (section 17, Title 17, US Code), without permission from the copyright owner, Society for General Microbiology. The Society for General Microbiology disclaims any responsibility or liability for errors or omissions in this version of the manuscript or in any version derived from it by any other parties. The final copy-edited, published article, which is the version of record, can be found at http://mic.sgmjournals.org, and is freely available without a subscription.International audiencePenicillium glabrum is a filamentous fungus frequently involved in food contamination. Numerous environmental factors (temperature, humidity, atmosphere composition, etc.) or food characteristics (water activity, pH, preservatives, etc.) could represent potential sources of stress for micro-organisms. These factors can directly affect physiology of these spoilage micro-organisms: growth, conidiation, synthesis of secondary metabolites, etc. This study investigates the transcriptional response to temperature in P. glabrum, since this factor is one of the most important for fungal growth. Gene expression was first analysed by using suppression subtractive hybridization to generate two libraries containing 445 different up- and down-regulated Expressed Sequenced Tags (ESTs). Expression of these ESTs was then assessed for different thermal stress conditions, with cDNA microarrays, resulting in the identification of 35 and 49 significantly up- and down-regulated ESTs, respectively. These ESTs encode heat shock proteins, ribosomal proteins, superoxide dismutase, trehalose-6-phosphate synthase and a large variety of identified or unknown proteins. Some of them may be potential molecular markers for thermal stress response in P. glabrum. To our knowledge, this work represents the first study of the transcriptional response of a food spoilage filamentous fungus under thermal stress conditions