Recent advances underpinning innovative strategies for the future.

It is instructive to evaluate recent evidence as presented in the preceding chapters of this volume. It is immediately clear that significant advances have been reported on the mainstream biochemistry of all the major families of amino acids in a diverse range of microorganisms. Emerging developments include enhanced understanding and manipulation of gene expression, the evaluation of enzyme structure-function relationships, assessment of the relative importance of competing biochemical pathways and elucidation of mechanisms of transcriptional and post-translational regulation. There has also been considerable understanding gained of the peripheral pathways of amino acid metabolism, particularly in certain bacteria. In addition, there is a perceptible shift in focus over recent years towards unlocking practical value for the potential resolution of intractable issues in food quality and safety, pathogen characterization, host-pathogen interactions and drug resistance. This change in emphasis is based on the premise that amino acid metabolism is a fundamental determinant of microbial viability, growth, pathogenicity and virulence.