Analysis of the O-antigen chain length distribution during extracellular and intracellular growth of Shigella flexneri

This study has established that there were no changes in the general struct ure of LPS of Shigella flexneri M90T either when the bacteria grew free in the cytoplasm of the eucaryotic host cell or during extracellular growth in liquid LB medium at 37 degreesC. In both cases there was a similar bimodal O-antigen chain length distribution with the mean modal values between 1 a nd 2, and between 11 and 14 subunits. This suggests that the intracellular localization is not a significant stimulus perceived by Shigella to regulat e the length of its O-side chains. However, when the bacteria grew under extracellular conditions (liquid medi um) at 30 degreesC, even though there were no changes in the modal values, the pattern of the O-antigen chain length distribution of LPS was different , with an increase in the amount of the long chains relative to the short c hains.