Functions of rpoS gene in response to environmental stress by Enterobacter sp. CGMCC 5087

Abstract:

[Background] 2-phenylethanol is a high-grade flavoring additive with rosy scent, and widely used in perfume, cosmetics, food and medicine. At present, the synthesis of 2-phenylethanol by engineering bacteria has a good prospect. We isolated an Enterobacter sp. CGMCC 5087 that can synthesize 2-phenylethanol through phenylpyruvate pathway. However, the growth of the bacterium and 2-phenylethanol yield are affected by environmental stress. As a stationary phase Sigma factor and a major regulator in response to stress, RpoS plays an important role in resistant to environmental stress. [Objective] In order to elucidate the role of rpoS gene in Enterobacter sp. CGMCC 5087 under various environmental stresses. [Methods] Using CRISPR gene editing technology to knockout the rpoS gene, and the complementary strain was constructed by introducing the plasmid containing rpoS gene into ΔrpoS strain. The growth of rpoS gene-deficient strain ΔrpoS, the wild-type strain and complementary strain ΔrpoS(rpoS) under high osmotic pressure, high temperature, low pH and oxidative stress environments was detected and statistically analyzed. [Results] Deletion of rpoS gene significantly reduced the growth of Enterobacter sp. CGMCC 5087 strain. Under the stress of 5% NaCl and pH 5.0, deletion of rpoS gene significantly reduced the tolerance of Enterobacter sp. CGMCC 5087. At 42 °C, the deletion of rpoS gene resulted in a significant decrease in the tolerance of Enterobacter sp. CGMCC 5087 in logarithmic phase, and increased during the decline phase. Under the condition of 1 mmol/L H2O2 oxidation stress, the deletion of rpoS gene led to the prolongation of the delay period of Enterobacter sp. CGMCC 5087, and the tolerance of the mutant strain ΔrpoS was significantly higher than that of the wild type. [Conclusion] In Enterobacter sp. CGMCC 5087, RpoS plays an important role in resisting to various environmental stresses, and the response to environmental stresses varies with the different growth periods of bacteria. The study provides a basis for further understanding of the biological characteristics of Enterobacter sp. CGMCC 5087 and the mechanism of RpoS in the synthesis of 2-phenylethanol of Enterobacter sp. CGMCC 5087.