Metabolism high-value metabolites

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 ... 

Primary metabolites are produced in larger quantities than the secondary metabolites and have specific metabolic functions. Primary metabolites obtained from higher plants are used as foods, food additives, and industrial raw materials, such as carbohydrates, vegetable oils, protein, and fatty acids. They are generally high-volume, low-value bulk materials. 

The nutritional value of the diet influences the ability of herbivores to detoxify plant secondary metabolites (Schwass and Finley, 1985). For instance, voles in winter have to consume the bark of birch Betula sp.). This causes stress and leads to poor growth and high mortality among young animals. Birch bark contains phenolics and terpenoids. Both are metabolized by cytochrome P450 monooxidases in phase I and conjugated with glucuronic acid in phase II. 

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