Project description:Anaerobic bacteria in the oral cavity can cause respiratory infections. However, their precise mechanisms of action remain elusive. Unexpectedly, bacterial flora analysis using 16s rRNA revealed ‘hidden’ mixed infections of anaerobic bacteria and commensal oral Streptococcus species in community-acquired pneumonia. The purpose of this study is to elucidate the mechanisms by which Prevotella intermedia exacerbates oral streptococcal pneumonia.
Project description:we performed time series microarray analyses to investigate transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration. Published on J. Bacteriol., 190 (1), 286-299, 2008. Major changes in gene expression profiles occurred in the initial 15 min after the shift from anaerobic-light to aerobic-dark conditions, with changes continuing to occur up to 4 hours postshift. Those genes whose expression levels changed significantly during the time series were grouped into three major classes by clustering analysis. Class I contained genes, such as that for the aa3 cytochrome oxidase, whose expression levels increased after the shift. Class II contained genes, such as those for the photosynthetic apparatus and Calvin cycle enzymes, whose expression levels decreased after the shift. Class III contained genes whose expression levels temporarily increased during the time series. Keywords: time course
Project description:Osmotic changes are common challenges for marine microorganisms. Bacteria developed numerous ways of dealing with this stress, including reprogramming of global cellular processes, however, many molecular details were obtained only for the model bacteria. In this work we asked what is the basis of the adjustment to prolonged salinity challenges at the proteome level. The objects of our studies were three representatives of bacteria inhabiting various marine environments, Shewanella baltica, Vibrio harveyi and Aliivibrio fischeri. The proteomic studies were performed with bacteria cultivated in increased and decreased salinity, followed by proteolytic digestion of samples which were then subjected to liquid chromatography with tandem mass spectrometry analysis. We show that bacteria adjust at all levels of their biological processes, from DNA topology through gene expression regulation and proteasome assembly, to transport and cellular metabolism. Finding that many similar adaptation strategies were observed for both, low and high salinity conditions, is particularly interesting. The results show that adaptation to salinity challenge involves accumulation of DNA-binding proteins and increased polyamine uptake, and we hypothesize that their function is to coat and protect the nucleoid to counteract adverse changes in the DNA topology due to ionic shifts.