Abstract
BackgroundTranscriptional engineering has presented a strong ability of phenotypic improvement in microorganisms. However, it could not be directly applied to Actinoplanes teichomyceticus L-27 because of the paucity of endogenous transcription factors in the strain. In this study, exogenous transcription factors were rationally selected and transcriptional engineering was carried out to increase the productivity of teicoplanin in L-27.ResultsIt was illuminated that the σHrdB molecules shared strong similarity of amino acid sequences among some genera of actinomycetes. Combining this advantage with the ability of transcriptional engineering, exogenous sigma factor σHrdB molecules were rationally selected and engineered to improve L-27. hrdB genes from Actinoplanes missouriensis 431, Micromonospora aurantiaca ATCC 27029 and Salinispora arenicola CNS-205 were selected based on molecular evolutionary analysis. Random mutagenesis, DNA shuffling and point mutation were subsequently performed to generate diversified mutants. A recombinant was identified through screening program, yielding 5.3 mg/ml of teicoplanin, over 2-fold compared to that of L-27. More significantly, the engineered strain presented a good performance in 500-l pilot scale fermentation, which meant its valuable potential application in industry.ConclusionsThrough rational selection and engineering of exogenous transcriptional factor, we have extended the application of transcriptional engineering. To our knowledge, it is the first time to focus on the related issue. In addition, possessing the advantage of efficient metabolic perturbation in transcription level, this strategy could be useful in analyzing metabolic and physiological mechanisms of strains, especially those with the only information on taxonomy.
Highlights
Many microorganisms have been developed as cell factories to produce bioactive chemicals
The transcriptional engineering has been successfully applied in yeast [9], Escherichia coli [10] and Lactobacillus plantarum [11]
Since A. teichomyceticus L-27 possessed the taxonomic status of Actinoplanes genus in actinomycetes, the neighbor-joining phylogenetic tree of several strains in typical actinomycete genera was constructed based on amino acid sequences of σHrdB
Summary
Many microorganisms have been developed as cell factories to produce bioactive chemicals. Considering its strong capability of regulating diverse metabolic and physiological functions, this approach is urgently used to engineer more strains, especially the industrial valuable and newly explored ones. Transcriptional engineering has presented a strong ability of phenotypic improvement in microorganisms. Exogenous transcription factors were rationally selected and transcriptional engineering was carried out to increase the productivity of teicoplanin in L-27. Results: It was illuminated that the σHrdB molecules shared strong similarity of amino acid sequences among some genera of actinomycetes. Combining this advantage with the ability of transcriptional engineering, exogenous sigma factor σHrdB molecules were rationally selected and engineered to improve L-27. The engineered strain presented a good performance in 500-l pilot scale fermentation, which meant its valuable potential application in industry
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