Adaptation of Brucella suis and Brucella microti to acid stress in minimal medium at pH 4.5

The atypical new species Brucella microti, isolated from wild animals and a very close relative of the classical zoonotic species Brucella suis bv. 1 1330, is fast growing and lethal in mice. Both species represent an appropriate model for classical/atypical Brucella spp. comparisons. Despite highly conserved genome sequences with over 99 % identity, these species are phenotypically distinct from one another and developed species-specific responses to acid stress. The more acid-resistant phenotype of B. microti may have major implications in fitness and virulence, influencing bacterial survival in soil and in host. The goal of this study is the characterization of the acid resistance determinants of both species by an in vitro comparative RNAseq-based transcriptome analysis in minimal medium at pH 4.5 and 7.0. This study allows a thorough, comparative analysis of global transcriptional regulation during acid stress responses of a classical and an atypical Brucella spp. and contributes to a better understanding of species-specific phenotypes during adaptation to acid environments.