We aimed to overexpress the ‘tesA gene (which codes for thioesterase I) in E. coli to (1) enhance the conversion of fatty acyl-CoA to free fatty acid, and (2) bypass the β-oxidation pathway for fatty acid metabolism. To facilitate this strategy, we have subcloned the ‘tesA coding sequence downstream of the PBAD promoter in the pSB1C3 vector. E. coli TOP10 cells (Invitrogen) was used as the host to overexpress ‘tesA. Expression of the ‘tesA gene was measured by quantitative RT-PCR and the effect of ‘TesA overexpression (leading to a possible increase in thioesterase I activity) was indirectly tested by determining the oleic acid concentrations in control and ‘tesA recombinant E. coli cells by GC-MS.