A rapid method for the preparation of lipid A from Yersinia pseudotuberculosis

The possibility of preparing the lipid A (LA) from Yersinia pseudotuberculo sis Serovar IB by the hydrolysis of whole cells instead of the preliminary isolation of lipopolysaccharide (LPS) was demonstrated. Direct extraction w ith an organic solvent of the bacterial mass preliminarily treated with 10% acetic acid or 1 M HCl was shown to result in a di- (LA(AcOH)) or monophos phoryl derivative (LA(HCl)), respectively. These were completely extractabl e only after treatment with strong hydrolyzing agents. We concluded that tw o forms of LA (and LPS) exist in the pseudotuberculosis bacterium which dif fer in the stability of their bonding to the bacterial outer membrane.