title: Production of ε-poly-L: -lysine using a novel two-stage pH control strategy by Streptomyces sp. M-Z18 from glycerol.
abstract: The production of ε-poly-L: -lysine (ε-PL) by Streptomyces sp. M-Z18 from glycerol was investigated in a 5-L jar-fermenter. Batch fermentations by Streptomyces sp. M-Z18 at various pH values ranging from 3.5 to 4.5 were studied. Based on the analysis of the time course of specific cell growth rate and specific ε-PL formation rate, a novel two-stage pH control strategy was developed to improve ε-PL production by shifting the culture pH from 3.5 to 3.8 after 36 h of cultivation. By applying the strategy, the maximal ε-PL concentration and productivity had a significant improvement and reached 9.13 g L(-1) and 4.76 g L(-1) day(-1), respectively, compared with those in one-stage pH control process where the pH value is controlled at 3.5 (7.83 g L(-1) and 3.13 g L(-1) day(-1)). Fed-batch fermentation with two-stage pH control strategy was also applied to produce ε-PL; final ε-PL concentration of 30.11 g L(-1) was obtained, being 3.3-fold greater than that of batch fermentation. To our knowledge, it is the first report on production of ε-PL from glycerol in fermenter scale and achievement of high ε-PL production with two-stage pH control strategy.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, Jiangsu, China.
authors.forename: Xu-Sheng
authors.initials: XS
authors.lastname: Chen
authors.forename: Shu
authors.initials: S
authors.lastname: Li
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Liao
authors.forename: Xi-Dong
authors.initials: XD
authors.lastname: Ren
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhang
authors.forename: Zhong-Gui
authors.initials: ZG
authors.lastname: Mao
mesh_terms: D019149:Bioreactors; D005285:Fermentation; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods*; D011107:Polylysine / Q000096:biosynthesis*; D013302:Streptomyces / Q000254:growth & development / Q000378:metabolism
chemical_list: D011107:Polylysine; D005990:Glycerol