title: Enhancement of ε-poly-L-lysine production coupled with precursor L-lysine feeding in glucose-glycerol co-fermentation by Streptomyces sp. M-Z18.
abstract: ε-Poly-L-lysine (ε-PL), one of the only two homo-poly amino acids known in nature, is used as a preservative. In this study, strategies of feeding precursor L-lysine into 5 L laboratory scale fermenters, including optimization of L-lysine concentration and time, was investigated to optimize the production of ε-PL by Streptomyces sp. M-Z18. The optimized strategy was then used in ε-PL fed-batch fermentation in which glucose and glycerol served as mixed carbon sources. In this way, a novel ε-PL production strategy involving precursor L-lysine coupled with glucose-glycerol co-fermentation was developed. Under optimal conditions, ε-PL production reached 37.6 g/l, which was 6.2 % greater than in a previous study in which glucose and glycerol co-fermentation was performed without added L-lysine (35.14 g/l). To the best of our knowledge, this is the first report of the enhancement of ε-PL production through L-lysine feeding to evaluate the use of fermenters. Meanwhile, the role of L-lysine in the promotion of ε-PL production, participating ε-PL synthesis as a whole, was first determined using the L-[U-(13)C] lysine labeling method. It has been suggested that the bottleneck of ε-PL synthesis in Streptomyces sp. M-Z18 is in the biosynthesis of precursor L-lysine. The information obtained in the present work may facilitate strain improvement and efficient large-scale ε-PL production.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
authors.forename: Xu-Sheng
authors.initials: XS
authors.lastname: Chen
authors.forename: Xi-Dong
authors.initials: XD
authors.lastname: Ren
authors.forename: Xin
authors.initials: X
authors.lastname: Zeng
authors.forename: Fu-Lin
authors.initials: FL
authors.lastname: Zhao
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.forename: Hong-Jian
authors.initials: HJ
authors.lastname: Zhang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhang
authors.forename: Zhong-Gui
authors.initials: ZG
authors.lastname: Mao
mesh_terms: D018533:Biomass; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D011107:Polylysine / Q000096:biosynthesis*; D013302:Streptomyces / Q000378:metabolism*
chemical_list: D011107:Polylysine; D005947:Glucose; D008239:Lysine; D005990:Glycerol