title: [Enhanced ε-poly-L-lysine production by improving cellular activity during fermentation].
abstract: OBJECTIVE
  To assess the effect of cellular activity on ε-poly-1-lysine (ε-PL) biosynthesis and thereby to rationally improve the production, we studied the cellular activity, ε-PL formation and other parameters cross flask fermentation by Streptomyces ahygroscopicus.
  
  
  METHODS
  Laser scanning confocal microscopy and a colorimetric method were used to determine cellular activity using BacLight Live/Dead and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) as viable stains. To enhance the activity of the cells in the ε-PL production period, yeast extract was added.
  
  
  RESULTS
  During ε-PL submerged fermentation in flasks, most cells were active in the growth period (0 - 16 h); cells had metabolic activity in the growth and earlier ε-PL production periods between 0 and 30 h fermentation. Almost no activity was detected after 48 h fermentation when no ε-PL was produced. The improved fermentation achieved 2. 24 g/L ε-PL from 1.04 g/L.
  
  
  CONCLUSIONS
  Biosynthesis of ε-PL can be boosted by up-regulating cell activity in its production phase.
authors.forename: Shengrong
authors.initials: S
authors.lastname: Liu
authors.forename: Qingping
authors.initials: Q
authors.lastname: Wu
authors.forename: Jumei
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Yang
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Cai
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D003470:Culture Media / Q000378:metabolism; D005285:Fermentation; D011107:Polylysine / Q000096:biosynthesis*; D013302:Streptomyces / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003470:Culture Media; D011107:Polylysine