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Background Escherichia coli has been proved to be one promising platform chassis for the production of various natural products, such as biofuels. Product toxicity is one of the main bottlenecks for achieving maximum production of biofuels. Host strain engineering is an effective approach to alleviate solvent toxicity issue in fermentation. Results Thirty chaperones were overexpressed in E. coli JM109, and SecB recombinant strain was identified with the highest n -butanol tolerance. The tolerance ( T ) of E. coli overexpressing SecB, calculated by growth difference in the presence and absence of solvents, was determined to be 9.13% at 1.2% (v/v) butanol, which was 3.2-fold of the control strain. Random mutagenesis of SecB was implemented and homologously overexpressed in E. coli , and mutant SecB T10A was identified from 2800 variants rendering E. coli the highest butanol tolerance. Saturation mutagenesis on T10 site revealed that hydrophobic residues were required for high butanol tolerance of E. coli . Compared with wild-type (WT) SecB, the T of SecB T10A strain was further increased from 9.14 to 14.4% at 1.2% butanol, which was 5.3-fold of control strain. Remarkably, E. coli engineered with SecB T10A could tolerate as high as 1.8% butanol (~ 14.58 g/L). The binding affinity of SecB T10A toward model substrate unfolded maltose binding protein (preMBP) was 11.9-fold of that of WT SecB as determined by isothermal titration calorimetry. Residue T10 locates at the entrance of hydrophobic substrate binding groove of SecB, and might play an important role in recognition and binding of cargo proteins. Conclusions SecB chaperone was identified by chaperone mining to be effective in enhancing butanol tolerance of E. coli . Maximum butanol tolerance of E. coli could reach 1.6% and 1.8% butanol by engineering single gene of SecB or SecB T10A . Hydrophobic interaction is vital for enhanced binding affinity between SecB and cargo proteins, and therefore improved butanol tolerance. Electronic supplementary material The online version of this article (10.1186/s13068-019-1507-7) contains supplementary material, which is available to authorized users.

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Background Plants are constantly threatened by various pathogens in a challenging environment. Altemaria panax Whetzel is a destructive pathogen that affects many plants, including Panax notoginseng, and significantly reduces the yield and product quality of Panax notoginseng. It is not clear how Panax notoginseng responds to pathogen infection.Methods Using the advanced advantages of transcriptome and proteomics technology, we studied the response of Panax notoginseng to Altemaria panax stress.Results Compared with the control, fungal infection caused significant changes in the Panax notoginseng transcriptome and proteome. Specifically, a total of 136,100 transcripts and 4,468 proteins were identified. The integration of transcriptome and proteome profiles revealed many candidate transcripts/proteins, which may be involved in lignin synthesis during the activation of defense responses by Panax notoginseng. Many genes and proteins are induced or inhibited by fungi. Among them, the expression levels of genes PAL, 4CL, COMT, CAD and POX in the lignin synthesis pathway are significantly increased, which indicates that the fungus activates the defense response of Panax notoginseng.Conclusions As far as we know, this is the first time that transcriptome and proteome analysis have been combined to study the response of Panax notoginseng to disease. This study provides a wide range of new information about the transcriptome, proteome and their correlation of Panax notoginseng in response to fungal stress. The analysis of this resource allows us to examine the mechanisms of transcription and protein diversification, which expands the knowledge of the complexities of the transcriptome and proteome in traditional Chinese medicines.