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Open AccessArticle

Transcriptional Changes in the Xylose Operon in Bacillus licheniformis and Their Use in Fermentation Optimization

by 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3, 1,2,3 and 1,2,3,*
1
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China
2
National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
3
Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2019, 20(18), 4615; https://doi.org/10.3390/ijms20184615
Received: 30 August 2019 / Revised: 14 September 2019 / Accepted: 16 September 2019 / Published: 18 September 2019
(This article belongs to the Section Molecular Microbiology)
The xylose operon is an efficient biological element used for the regulation of gene expression in Bacillus licheniformis. Although the mechanism underlying the xylose-mediated regulation of this operon has been elucidated, the transcriptional changes that occur under various fermentation conditions remain unclear. In this study, the effects of different conditions on xylose operon expression were investigated. Significant upregulation was observed during the transition from the logarithmic phase to the stationary phase (2.5-fold, n = 3, p < 0.01). Glucose suppressed transcription over 168-fold (n = 3, p < 0.01). Meanwhile, the inhibitory effect of glucose hardly strengthened at concentrations from 20 to 180 g/L. Furthermore, the transcription of the xylose operon increased at elevated temperatures (25–42 °C) and was optimal at a neutral pH (pH 6.5–7.0). Based on these findings, relevant fermentation strategies (delaying the induction time, using dextrin as a carbon source, increasing the fermentation temperature, and maintaining a neutral pH) were proposed. Subsequently, these strategies were validated through the use of maltogenic amylase as a reporter protein, as an 8-fold (n = 3, p < 0.01) increase in recombinant enzyme activity compared to that under unoptimized conditions was observed. This work contributes to the development of fermentation optimization and furthers the use of the xylose operon as an efficient expression element. View Full-Text
Keywords: Bacillus licheniformis; transcriptional changes; xylose operon; fermentation optimization; expression element Bacillus licheniformis; transcriptional changes; xylose operon; fermentation optimization; expression element
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Li, Y.; Liu, X.; Zhang, L.; Ding, Z.; Xu, S.; Gu, Z.; Shi, G. Transcriptional Changes in the Xylose Operon in Bacillus licheniformis and Their Use in Fermentation Optimization. Int. J. Mol. Sci. 2019, 20, 4615.

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