Characterization of Escherichia coli MG1655 grown in a low-shear modeled microgravity environment.
BACKGROUND
Extra-cellular shear force is an important environmental parameter that is significant both medically and in the space environment. Escherichia coli cells grown in a low-shear modeled microgravity (LSMMG) environment produced in a high aspect rotating vessel (HARV) were subjected to transcriptional and physiological analysis.


RESULTS
Aerobic LSMMG cultures were grown in rich (LB) and minimal (MOPS + glucose) medium with a normal gravity vector HARV control. Reproducible changes in transcription were seen, but no specific LSMMG responsive genes were identified. Instead, absence of shear and a randomized gravity vector appears to cause local extra-cellular environmental changes, which elicit reproducible cellular responses. In minimal media, the majority of the significantly up- or down-regulated genes of known function were associated with the cell envelope. In rich medium, most LSMMG down-regulated genes were involved in translation. No observable changes in post-culture stress responses and antibiotic sensitivity were seen in cells immediately after exposure to LSMMG. Comparison with earlier studies of Salmonella enterica serovar Typhimurium conducted under similar growth conditions, revealed essentially no similarity in the genes that were significantly up- or down-regulated.


CONCLUSIONS
Comparison of these results to previous studies suggests that different organisms may dramatically differ in their responses to medically significant low-shear and space environments. Depending on their specific response, some organisms, such as Salmonella, may become preadapted in a manner that predisposes them to increased virulence.
Tucker
Don L
DL
University of Houston, Department of Biology & Biochemistry, Houston, TX 77204-5001, USA. dtucker84@yahoo.com <dtucker84@yahoo.com>
Ott
C Mark
CM
Huff
Stephen
S
Fofanov
Yuriy
Y
Pierson
Duane L
DL
Willson
Richard C
RC
Fox
George E
GE
D000332:Aerobiosis; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003470:Culture Media / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014893:Weightlessness
D000900:Anti-Bacterial Agents; D003470:Culture Media