During the production of ε-poly-L-lysine (ε-PL) in fed-batch fermentation, the decline of ε-PL synthesis often occurs at middle or late phase of the fermentation. To solve the problem, we adopted two strategies, namely pH shift and feeding yeast extract, to improve the productivity of ε-PL. ε-PL productivity in fermentation by pH shift and feeding yeast extract achieved 4.62 g/(L x d) and 5.16 g/(L x d), which were increased by 27.3% and 42.2% compared with the control ε-PL fed-batch fermentation, respectively. Meanwhile, ε-PL production enhanced 36.95 g/L and 41.32 g/L in 192 h with these two strategies, increased by 27.4% and 42.48% compared to the control, respectively. ε-PL production could be improved at middle or late phase of fed-batch fermentation by pH shift or feeding yeast extract.
Batch Cell Culture Techniques ; Fermentation ; Industrial Microbiology ; Nitrogen ; chemistry ; Polylysine ; biosynthesis

Objective To develop a human Tim-3 specific monoclonal antibody and evaluate its biological activity and possible use in clinical diseases associated with dysregulated Tim-3 expression .Methods The BALB/c mice were immu-nized by conventional method, and positive clones were used to develop anti-human Tim-3 antibody, the binding and neutralization activities of which in vitro and in vivo were investigated.Results ①A monoclonal antibody (clone L3D) which could specifically bind to human Tim-3 protein in ELISA assay was obtained and the subtype of the monoclonal antibody was IgG2a .②Flow cytometry indicated that the monoclonal antibody could bind to Tim-3 expressed in human U937 cells.This antibody also showed a cross activity to mice′Tim-3.③The monoclonal antibody inhibited the apoptosis of THP1 cells induced by Gal-9, the ligand of Tim-3.④Injection of Tim-3 antibody exacerbated sepsis in mice as marked by the decreased survival rate and increased expression of pro-inflammatory cytokines .Conclusion An anti-human Tim-3 monoclonal antibody is successfully obtained.The excellent binding and neutralization activities of this antibody enable it to be widely used in clinical diseases associated with deregulated Tim-3 expression .