Four bioengineered bacteria having the fasG gene were constructed using two Escherichia coli expression strains (BL21 (DE3) and Rossetta (DE3)) with different tRNA profiles and two E. coli expression vectors (pET28a(+) and pGEX-KG) to examine the influence of rare codons on the expression of the fasG gene. The induction expression result of bioengineered bacteria showed that the expression levels of target proteins in Rossetta (DE3), which contained the tRNAs of the rare codons, were higher than in BL21 (DE3), either using pET-fasG or pKG-fasG.