The overwhelming majority of antibiotics in clinical use are natural products isolated from Actinobacteria or semi-synthetic derivatives.Pathogenic microorganisms are becoming increasingly resistant to these compounds,and there is thus an urgent need to discover novel antibiotics to address the emerging health threat this poses.In contrast to Actinobacteria,which are a Gram-positive,the potential of Gram-negative bacteria to produce antibiotics has been relatively underexplored.In this lecture I will discuss our recent efforts to investigate the production of antibiotics by Burkolderia and other Gram-negative bacterial genera.These have led to the discovery of novel polyketides with potent activity against important antibiotic-resistant pathogens such as Mycobacterium tuberculosis and Acinetobacter baumannii.They have also identified Burkholderia bacteria as the true producers of an interesting group of nonribosomal peptide antibiotics previously isolated ft-oni filamentous fungi.The gene clusters responsible for the biosynthesis of these metabolites have been identified and efforts to understand the biosynthetic pathways they encode will be discussed.The manipulation of one of the biosynthetic gene clusters to produce novel antibiotic analogues that provide insight into the natural products structure-activity relationship will also be presented.