title: A transcriptional study of acidogenic chemostat cells of Clostridium acetobutylicum--cellular behavior in adaptation to n-butanol.
abstract: To gain more insight into the butanol stress response of Clostridium acetobutylicum the transcriptional response of a steady state acidogenic culture to different levels of n-butanol (0.25-1%) was investigated. No effect was observed on the fermentation pattern and expression of typical solvent genes (aad, ctfA/B, adc, bdhA/B, ptb, buk). Elevated levels of butanol mainly affected class I heat-shock genes (hrcA, grpE, dnaK, dnaJ, groES, groEL, hsp90), which were upregulated in a dose- and time-dependent manner, and genes encoding proteins involved in the membrane composition (fab and fad or glycerophospholipid related genes) and various ABC-transporters of unknown specificity. Interestingly, fab and fad genes were embedded in a large, entirely repressed cluster (CAC1988-CAC2019), which inter alia encoded an iron-specific ABC-transporter and molybdenum-cofactor synthesis proteins. Of the glycerophospholipid metabolism, the glycerol-3-phosphate dehydrogenase (glpA) gene was highly upregulated, whereas a glycerophosphodiester ABC-transporter (ugpAEBC) and a phosphodiesterase (ugpC) were repressed. On the megaplasmid, only a few genes showed differential expression, e.g. a rare lipoprotein (CAP0058, repressed) and a membrane protein (CAP0102, upregulated) gene. Observed transcriptional responses suggest that C. acetobutylicum reacts to butanol stress by induction of the general stress response and changing its cell envelope and transporter composition, but leaving the central catabolism unaffected.
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
authors.forename: Katrin M
authors.initials: KM
authors.lastname: Schwarz
authors.forename: Wouter
authors.initials: W
authors.lastname: Kuit
authors.forename: Christina
authors.initials: C
authors.lastname: Grimmler
authors.forename: Armin
authors.initials: A
authors.lastname: Ehrenreich
authors.forename: Servé W M
authors.initials: SW
authors.lastname: Kengen
mesh_terms: D020001:1-Butanol / Q000494:pharmacology*; D000143:Acids / Q000378:metabolism*; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D019149:Bioreactors / Q000382:microbiology*; D046969:Clostridium acetobutylicum / Q000166:cytology* / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D008954:Models, Biological; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000143:Acids; D012097:Repressor Proteins; D020001:1-Butanol