Mechanistic Insight into Phenolic Compounds Toxicity and State-of-the-art Strategies for Enhancing the Tolerance of Escherichia coli to Phenolic Compounds

Efficient use of lignocellulosic biomass is a prerequisite for sustainable biofuel production while simultaneously contributing to environmental protection. However, phenolic compounds produced during the chemical treatment of lignocellulose inhibit the growth and metabolism of microorganisms, such as Escherichia coli, which is one of the ideal strains for producing target products by microbial fermentation. To provide new ideas for studying microbial tolerance to environmental stress and providing technical support for constructing the engineering strains with high yields of phenolic compounds, this review elucidates the inhibition mechanism of phenols to E. coli. Secondly, a comprehensive and systematic review of current approaches for improving the phenolic-tolerance of E. coli is provided, including strain domestication, random mutagenesis, regulating the expression of outer membrane proteins, changing the composition of membrane fatty acids, accelerating the efflux of phenolic compounds, engineered bacterial biofloc formation, and transcriptome analysis. Finally, this review ends with some questions that still exist today, and prospective strategies are outlined for further improving the phenols-tolerance of E. coli. This review provided a theoretical basis for research into microbial tolerance to environmental stress and the development of engineered strains with high yield of phenolic compounds.