title: [Optimization of biotransformation of ursolic acid by alternaria longipes].
abstract: OBJECTIVE
  To conduct the biotransformation of ursolic acid by alternaria longipes AS3. 2875, and optimize the culture medium and biotransformation conditions.
  
  
  METHODS
  With the consumption rate of ursolic acid and the generation rate of 28-O-beta-D-glucopyranose ursolic acid as indicators, the impact of different biotransformation conditions such as pH, phosphate, different kinds of metal ions, spore concentration, substrate quantity, temperature, shaking speed and cultivation time on the transformation of ursolic acid in alternaria longipes culture solution were detected to obtain the optimal biotransformation conditions of ursolic acid by alternaria longipes.
  
  
  RESULTS
  The optimized biotransformation conditions were as follows: initial pH value was 5.0, MgSO4 was 0.25 g x L(-1) K2HPO4 was 1.0 g x L(-1), FeSO4 was 0.083 g x L(-1), spore concentration was 4%, substrate quantity was 0.3 g x L(-1), shaking speed was 140 r x min(-1), cultivation temperature was at 28 degrees C and cultivating time was 3 days.
  
  
  CONCLUSIONS
  The generation rate of 28-O-beta-D-glucopyranose ursolic acid by alternaria longipes stabilizes at around 5%.
authors.affiliation: Tianjin Key Laboratory for Biomarkers of Occupational and Environmental Hazard, Tianjin 300162, China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Yan
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Dailin
authors.initials: D
authors.lastname: Liu
mesh_terms: D000528:Alternaria / Q000737:chemistry / Q000378:metabolism*; D001711:Biotransformation; D003470:Culture Media / Q000378:metabolism; D046508:Culture Techniques / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D014315:Triterpenes / Q000032:analysis / Q000378:metabolism*; D000097245:Ursolic Acid
chemical_list: D003470:Culture Media; D014315:Triterpenes; D000097245:Ursolic Acid