<b>TẠO CHỦNG Escherichia coli CÓ KHẢ NĂNG CHỊU NỒNG ĐỘ ETHANOL CAO ĐỂ NÂNG CAO HIỆU QUẢ BIỂU HIỆN PROTEIN TÁI TỔ HỢP</b>

The <i>Escherichia coli</i> expression system is among the most widely used platforms for recombinant protein production. Beyond utilizing an efficient expression vector, selecting the appropriate host strain is critical for enhancing recombinant protein yields. This study employed an ethanol-adaptive laboratory evolution (ALE) approach to develop ethanol-tolerant strains of <i>E. coli</i> BL21(DE3) and C41(DE3), focusing on improving their growth rates and assessing their potential for recombinant protein production.The results revealed that the ethanol-adapted strains demonstrated enhanced ethanol tolerance and improved growth characteristics compared to the original strains. Specifically, four evolved strains—BL21(DE3)-LE, BL21(DE3)-ME, C41(DE3)-LE, and C41(DE3)-ME—exhibited ethanol tolerance increases of 1.4–1.5-fold over their parental strains. Furthermore, these evolved strains displayed distinct phenotypic and growth characteristics that differentiated them from the original strains.Preliminary PETase expression results identified BL21(DE3)-ME and C41(DE3)-ME as promising candidates for enhancing recombinant protein expression. Subsequent experiments confirmed that these adapted strains significantly improved the expression efficiency of various recombinant proteins, including PETase, AN3860 (AA9 PMO), and <i>Bst</i> DNA polymerase, compared to the original strains.