Construction of a Genetic System for Streptomyces albulus PD-1 and Improving Poly(ε-ʟ-lysine) Production Through Expression of Vitreoscilla Hemoglobin

• Published in: Journal of microbiology and biotechnology Vol. 25; no. 11; pp. 1819 - 1826
• Main Authors: Xu, Zhaoxian, Cao, Changhong, Sun, Zhuzhen, Li, Sha, Xu, Zheng, Feng, Xiaohai, Xu, Hong
• Format: Journal Article
• Language: Korean
• Published: 2015
• Subjects: dissolved oxygen; submerged fermentation; Streptomyces albulus; genetic system; Vitreoscilla hemoglobin; Poly(ε-ʟ-lysine)
• ISSN: 1017-7825; 1738-8872

Poly(ε-ʟ-lysine) (ε-PL) is a novel bioactive polymer secreted by filamentous bacteria. Owing to lack of a genetic system for most ε-PL-producing strains, very little research on enhancing ε-PL biosynthesis by genetic manipulation has been reported. In this study, an effective genetic system was established via intergeneric conjugal transfer for Streptomyces albulus PD-1, a famous ε-PL-producing strain. Using the established genetic system, the Vitreoscilla hemoglobin (VHb) gene was integrated into the chromosome of S. albulus PD-1 to alleviate oxygen limitation and to enhance the biosynthesis of ε-PL in submerged fermentation. Ultimately, the production of ε-PL increased from 22.7 g/l to 34.2 g/l after fed-batch culture in a 5 L bioreactor. Determination of the oxygen uptake rate, transcriptional level of ε-PL synthetase gene, and ATP level unveiled that the expression of VHb in S. albulus PD-1 enhanced ε-PL biosynthesis by improving respiration and ATP supply. To the best of our knowledge, this is the first report on enhancing ε-PL production by chromosomal integration of the VHb gene in an ε-PL-producing strain, and it will open a new avenue for ε-PL production.