Growth and division of Escherichia coli under microgravity conditions

Abstract

SUMMARYThe growth rate in glucose minimal medium and time of entry into the stationary phase in pepton cultures ware determined during the STS 42 mission of the space shuttle Dis. covery. Cells were cultured in plastic bags and growth was stopped at six different time points by lowering the temperature to 5°C, and at a single time point, by formaldehyde fixation. Based on cell number determination, the doubling time calculated for the flight samples of glucose cells was shorter (46 mini than for the ground samples (59 mini. However, a larger cell size expected for more rapidly growing cells was not observed by volume measurements with the electron'.,c particle counter, nor by eiccax)n microscopi(; measurement of cell dimensions. Only for ceils fixed in flight was a larger cell length and percentage of constricted cells found. An optical density increase -=n the peptone cultures shewed an earlier entry into the stationary phase in flight semples, but this could not be confirmed by viability counts. The single sample with cells fixed in flight showed properties indicative of gTowth stimulation. However, taking. ~H ~bservations together, we conclude that mFcrogravity has no effect on the growth rate of exponentially growing Escherichia coil cells.

Investigation of space flight effects on Escherichia coli and a proposed model of underlying physical mechanisms

“…Similar findings of shortened lag phase for bacteria have also previously been reported (Mennigmann & Lange, 1986;Manko et al, 1987), although Mennigmann & Heise (1994) later reported that the earlier finding may have been an artifact of specific test conditions. Additionally, while not directly reported as such, interpretation of growth curve data shown by Gasset et al (1994) and by Tixador et al (1994) also suggests the possibility that a shortened lag phase may have occurred in space. Given the incidence of reports, however uncertain, this phenomenon warrants further investigation.…”

“…Irrespective of intended experimental objectives, increased micro-organism proliferation in space has been reported by a majority of researchers (Mattoni, 1968 ;Tixador et al, 1985 ;Moatti et al, 1986;Lapchine et al, 1987Lapchine et al, ,1988Mennigmann & Lange, 1986;Ciferri et al, 1986). Others, however, have contradicted this finding (Bouloc & D'Ari, 1991;Gasset et al, 1994).…”

Microgravity Alters the Physiological Characteristics of Escherichia coli O157:H7 ATCC 35150, ATCC 43889, and ATCC 43895 under Different Nutrient Conditions

“…Several studies have examined bacterial growth under microgravity conditions (20,(36)(37)(38)(39)(40)(41)(42). The early study of microbes in a space environment reported that the growth of E. coli was no different in space than on Earth (36).…”

“…The early study of microbes in a space environment reported that the growth of E. coli was no different in space than on Earth (36). Gasset et al showed that the generation time of E. coli grown under microgravity conditions was slightly reduced compared with that of their NG counterparts, but there were no changes in bacterial cell size (37). Subsequent investigations of E. coli under LSMMG conditions reported a shortened lag phase, a longer exponential phase, and a doubling of the final cell population (38)(39)(40)(41).…”

BioRock: new experiments and hardware to investigate microbe–mineral interactions in space

“…One example of these problems is that some researchers have reported increased cell density of Escherichia coli in microgravity whilst others have not (Gasset et al 1994;Brown et al 2002). Kim et al (2013b) predict that these differences are due to changes in the growth medium and culture conditions.…”