Читать книгу Biomolecular Engineering Solutions for Renewable Specialty Chemicals - Группа авторов - Страница 42

Earlier biocommodities (up to some extent now also) were extracted from plants and animals leading to their overexploitation (Brower, 2008). Plants are the great source of secondary metabolites that have complex structures and used by humans, e.g. medicines, terpenes, flavoring and coloring agents, etc. (Facchini et al., 2012). Their yields are greatly affected by the time, climate, and other factors, which affect circadian rhythm of the plants (Li and Vederas, 2009). Moreover, the yields cannot satiate the current demand of the population. Being structurally complex in nature relying on chemical synthesis of the secondary metabolites is not feasible. Chemical synthesis also leads to toxicity of the end products and environmental pollution (Du et al., 2011). To overcome these challenges, the principles of genetic engineering explained in the earlier section are used to engineer microorganisms to become microbial cell factories to produce essential biocommodities such as bioplastic, biofuels, and antibiotics important to human welfare. Advancement in the knowledge of metabolic pathways for synthesis of secondary metabolites and full genome sequencing made fabrication of microbial cell factories easier (Keasling, 2012). Fabrication generally involves introduction of the gene of interest in the host organism so the heterologous pathway begins in it. It also includes exclusion of native pathways that are not crucial for the growth of the host organism (Tyo et al., 2007). Apart from the development of genetically modified strains, optimum conditions according to the product of interest and growth of strains is to be provided in a contained environment (bioreactor). This is done to observe the full potential of the strain (Kiss and Stephanopoulos, 1992).