Global transcriptome analysis of Stenotrophomonas maltophilia in response to growth at human body temperature

Abstract

Stenotrophomonas maltophilia (Smal) is a typical example of an environmental originated opportunistic human pathogen, which can thrive at different habitats including the human body and can cause a wide range of infections. It must cope with heat stress during transition from the environment to the human body as the physiological temperature of the human body (37 {square}) is higher than environmental niches (22-30 {square}). Interestingly, S. rhizophila a phylogenetic neighbour of Smal within genus Stenotrophomonas is unable to grow at 37 {square}. Thus, it is crucial to understand how Smal is adapted to human body temperature, which could suggest its evolution as an opportunistic human pathogen. In this study, we have performed comparative transcriptome analysis of S. maltophilia grown at 28 {square} and 37 {square} as temperature representative for environmental niches and human body respectively. RNA-Seq analysis revealed several interesting findings showing alterations in gene expression levels at 28 {square} and 37 {square}, which can play an important role during infection. We have observed downregulation of genes involved in cellular motility, energy production and metabolism, replication and repair whereas upregulation of VirB/D4 Type IV secretion system, aerotaxis, cation diffusion facilitator family transporter and LacI family transcriptional regulators at 37 {square}. Microscopy and plate assays corroborated altered expression of genes involved in motility. The results obtained enhance our understanding of the strategies employed by S. maltophilia during adaptation towards the human body. Impact statementStenotrophomonas maltophilia (Smal) is a WHO listed multidrug resistant nosocomial pathogen. Interestingly, S. maltophilia species can grow both at 28 {square} and 37 {square} unlike its closest taxonomic relative, i.e., S. rhizophila and also majority species belonging this genus. Hence this ability to grow at 37 {square}, i.e., human body temperature might have played key role in the unique success and emergence of this species as opportunistic human pathogen. Using transcriptome sequencing, we have identified set of genes which are differentially regulated at 37 {square} and investigated their evolutionary history. This study has revealed regulation of genes involved in motility, metabolism, energy, replication, transcription, aerotaxis and a type IV secretion system might have a role in successful adaption to a distinct lifestyle. The findings will be helpful in further systematic studies on understanding and management of an emerging human pathogen such as Smal.