title: Bioconversion of vitamin D3 to calcifediol by using resting cells of Pseudonocardia sp.
abstract: OBJECTIVE
  Resting cells of Pseudonocardia sp. KCTC 1029BP were used for the bioconversion of vitamin D3 to calcifediol which is widely used to treat osteomalacia and is industrially produced by chemical synthesis.
  
  
  RESULTS
  To obtain the maximum bioconversion yield of calcifediol by the microbial conversion of vitamin D3, a two-step optimization process was used, including the Plackett-Burman and the central composite designs. Six variables, namely agitation speed, aeration rate, resting cell concentration, vitamin D3 concentration, temperature, and pH, were monitored. Of these, aeration rate, resting cell concentration, and temperature were selected as key variables for calcifediol production and were optimized using the central composite design. Optimal bioconversion conditions obtained were as follows: aeration rate of 0.2 vvm, resting cell concentration of 4.7% w/v, and temperature of 33 °C.
  
  
  CONCLUSIONS
  Using the optimal conditions, 356 mg calcifediol l(-1) was obtained with a bioconversion yield of 59.4% in a 75 l fermentor. These are the highest values reported to date.
authors.affiliation: Department of Biotechnology, Graduate School, Korea University, Seoul, 136-713, Republic of Korea.
authors.forename: Dae-Jung
authors.initials: DJ
authors.lastname: Kang
authors.forename: Jong-Hyuk
authors.initials: JH
authors.lastname: Im
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Kang
authors.forename: Kyoung Heon
authors.initials: KH
authors.lastname: Kim
mesh_terms: D039903:Actinobacteria / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors; D002112:Calcifediol / Q000096:biosynthesis*; D002762:Cholecalciferol / Q000378:metabolism*; D007218:Industrial Microbiology; D012988:Soil Microbiology
chemical_list: D002762:Cholecalciferol; D002112:Calcifediol