The metabolites and enzymes synthesizedby microorganisms have been widely usedas food (Mitsuhashi, 2014; Wendisch,2014), pharmaceuticals (Elander, 2003;Endo, 2010), biofuels (Geddes et al.,2011), pesticides (Waldron et al., 2001;Yoon et al., 2004), and detergents(Shaligram and Singhal, 2010), as wellas in the manufacturing process of theseindustrial products (Kirk et al., 2002;Merino and Cherry, 2007). They playimportant roles in our daily lives. Theproduction methods used for usefulmetabolites and enzymes have improvedsince the time their importance was firstestablished.If the genes involved in the synthe-sis of a metabolite or enzyme of inter-est are unknown, the production yield isenhanced by introducing random muta-tions into the chromosomes of the syn-thesizing microbe by ultraviolet (UV)irradiation or treatment with mutagens(Adrio and Demain, 2006). In addition,culture conditions have been adaptedto further enhance production (Demain,2000; Mukherjee et al., 2006). On theother hand, if the genes involved areknown, their expression is also enhancedby metabolic engineering strategies suchas gene disruption and overexpressionusing genetic modification techniques(Stephanopoulos et al., 1998; Adrio andDemain, 2010). When genetic modifi-cation of the producing microorganismis not possible because of difficulties intransformation, heterologous expressionof the product of interest in other micro-bial species in which genetic modifica-tion can be more easily achieved hasalso been utilized for mass production(Stephanopoulos et al., 1998; Keasling,2012).Primary metabolites essential for thenormalgrowthoforganismsareconservedbetween closely related microbial species,and their metabolic pathways includinggenetic components are almost fully elu-cidated. Therefore, metabolic engineer-ing has been the chosen strategy usedfor increasing the microbial productionof primary metabolites (Stafford andStephanopoulos, 2001; Kern et al., 2007).About microbial enzymes, the codinggenes are highly likely to be identifiedif both N-terminal amino acid sequencesand molecular weights are not only iden-tified by using highly purified samples butthegenomicdataoftheproducermicroor-ganisms are also available. Searching agene from the genomic data, on the basisof the N-terminal amino acid sequenceand molecular weight, will help us iden-tifyanenzyme-codinggene.Oncethegenehas been identified, inducing overexpres-sion of this gene in the original produceror another microbial host is one of thestrategies adopted to increase the produc-tionoftheenzyme(DemainandVaishnav,2009).Four strategies are considered to beeffective in enhancing the productionof primary metabolites. The first strat-egy is enhancing the expression of genesinvolved in metabolite synthesis. Thisstrategy should be the most commonlyusedandreliableapproach,butitdoesnotalwayscontributetoelevatedproduc-tion. In fact, we enhanced the expres-sion of four enzyme genes, individually,that were involved in palmitic acid [C16-fatty acid] synthesis, aiming to increasethe production of free fatty acids (pri-mary metabolites) in