The last two decades of scientific research have progressed to the point where metabolic engineering, which involves the modifying of metabolic pathways of animals, plants, and bacterial cells at biochemical and molecular levels, is feasible. Conceptually, metabolic engineering takes into account the identification of major blocks or control points in a metabolic pathway at the molecular level followed by removal of these limitations with the help of various cellular engineering interventions. Understanding the metabolic pathways requires appropriate experiment setup, molecular biology and biochemistry methods, computational modelling, data analysis, and interpretation to allow the researchers to manipulate them as per their needs. This book comprises a total of 12 chapters from multiple contributors of different countries around the world, including Brazil, Egypt, India, Saudi Arabia, and Turkey. This book provides deep insight into the past, present, and future of metabolic engineering in the animal, microbial, and plant system, communicating interdisciplinary research and relevant results in biochemistry, molecular biology, applied microbiology, cellular physiology, cellular nutrition in health and disease, and biochemical engineering.