Wild-type metabolites, biosynthetic pathway

Transposon-based approaches have also been applied to myxobacteria (Figure 3). Mutants from transposon libraries can be analyzed chemically by comparison of their secondary metabolite profiles with the wild-type strain, or screened for altered bioactivity, for example, by overlay assays. This strategy was successfully used to identify the biosynthetic gene clusters responsible for the known metabolites tubulysin, disorazol, aurachin, and DKxanthene in the genomes of their respective producer strains, and has the potential to detect novel, as yet unidentified compounds and their corresponding biosynthetic pathways and regulatory elements (see Section 2.07.5). 

As pointed out by Bu lock the basic pathways of secondary metabolism have been free to radiate to many different end-products and often utilise enzymes of rather broad specificity. We have exploited the lack of enzyme specificity and shown that the mutant Bl-41a will metabolise structural analogues of the natural biosynthetic intermediates into the corresponding analogues of the normal secondary metabolites produced by the wild-type strains. The results are reviewed by Hedden et al. (16). 

Here, a portfolio of high-value metabolites produced by wild-type LAB displaying applications in the food, pharmaceutical, and chemical industries was presented. New approaches in the production of commodity chemicals, to replace natural resources, by recombinant LAB strains were briefly addressed. The versatility of this bacterial group demonstrates their potential to be used as cell factories beyond their classical use as food starter cultures, preservatives, or as probiotics. As shown, LAB are systematically screened for novel specific traits or applications thanks to the availability of novel molecular techniques and consumers demands for healthier, tailor-made foods. It is clear that application of LAB as the workhorses of the food industry has expanded to their use as microbial factories to increase yields and product repertoire which were earlier limited by the natural capacity of the existing bacterial biosynthetic pathways. Emerging fields include the design and creation of synthetic microbes to create novel metabolic pathways for new products. Will LAB be included in this next challenging approach ... 

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