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Discovery of a Short-Chain ε‑Poly‑l‑lysine and Its Highly Efficient Production via Synthetase Swap Strategy

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journal contribution
posted on 14.01.2019, 00:00 by Delei Xu, Rui Wang, Zhaoxian Xu, Zheng Xu, Sha Li, Mingxuan Wang, Xiaohai Feng, Hong Xu
ε-Poly-l-lysine (ε-PL) is a natural antimicrobial cationic peptide, which is generally recognized as safe for use as a food preservative. To date, the production capacity of strains that produce low-molecular weight ε-PL remains very low and thus unsuitable for industrial production. Here, we report a new low-molecular weight ε-PL-producing Kitasatospora aureofaciens strain. The ε-PL synthase gene of this strain was cloned into a high ε-PL-producing Streptomyces albulus strain. The resulting recombinant strain efficiently produced ε-PL with a molecular weight of 1.3–2.3 kDa and yielded of 23.6 g/L following fed-batch fermentation in a 5 L bioreactor. In addition, circular dichroism spectra showed that this ε-PL takes on a conformation similar to an antiparallel pleated-sheet. Moreover, it demonstrated better antimicrobial activity against yeast compared to the 3.2–4.5 kDa ε-PL. This study provides a highly efficient strategy for production of the low-molecular weight ε-PL, which helps to expand its potential applications.