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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.

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Sixty-one strains of Corynebacterium group D2 were examined for their ability to adhere to human uroepithelial cells and to agglutinate human and guinea-pig erythrocytes. Strains were isolated from samples of two origins: urine of bacteriuric patients and healthy skin of patients without urinary infection. In addition, the isolates were examined by scanning and transmission electron microscopy. Heavy adherence to the uroepithelial cells but weak hemagglutination were noted. No statistical association was demonstrated between the adherence and the origin of the strains (65.2% of urinary isolates and 80% of healthy skin isolates were adherent). On transmission electron microscopy, a close association was observed between adherent bacteria and cells on thin sections and only few strains were piliated with negative staining. These results do not support a role of adherence as a predictor of pathogenicity of Corynebacterium group D2 which seems to act as an opportunistic pathogen in urinary tract infections.

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