A detailed knowledge of LPS biosynthesis is of the utmost importance in understanding the function of the outer membrane of Gram-negative bacteria. The regulation of LPS biosynthesis affects many more compartments of the bacterial cell than the outer membrane and thus contributes to the understanding of the physiology of Gram-negative bacteria in general, on the basis of which only mechanisms of virulence and antibiotic resistance can be studied to find new targets for antibacterial treatment. The study of LPS biosynthesis is also an excellent example to demonstrate the limitations of "genomics" and "proteomics", since secondary gene products can be studied only by the combined tools of molecular genetics, enzymology and analytical structural biochemistry. Thus, the door to the field of "glycomics" is opened.