Eco-Friendly Applications of Natural Secondary Metabolites and Status of Siderophores

Abstract

Living organisms are known to produce various metabolites during their life periods. These confer survival advantages and have been categorized as primary and secondary metabolites. Primary metabolites are essential for growth and produced by primary metabolic pathways such as glycolysis. However, there are certain other metabolic pathways arising from primary ones that are known to produce additional metabolites. These diverse classes of secondary metabolites are produced during late growth phase and are generally involved in stress responses, gaining competitive edge and other activities not essential for growth. Other than conferring selective advantage to its producer, secondary metabolites can be used for different purposes. Numerous microorganisms, plants, and some mammalian cells are known to produce specialized secondary metabolites called siderophores. These are low molecular weight non-ribosomal peptides involved in metal chelation with highest affinity toward iron. Different metabolic pathways involving several enzymatic and non-enzymatic steps exist for production of secondary metabolites. Secondary metabolites find numerous applications such as in bioremediation, medicine, biofuel production, and commercial purposes such as textiles and the cosmetics and food industries. In recent years, different strategies including specialized metabolic engineering for optimum production of secondary metabolites are being explored. This chapter discusses various aspects related to biosynthesis, production, and applications of different secondary metabolites with special emphasis on siderophores.