title: Optimization of a protective medium for freeze-dried Pichia membranifaciens and application of this biocontrol agent on citrus fruit.
abstract: OBJECTIVE
  To optimize a protective medium for freeze-dried Pichia membranifaciens and to evaluate biocontrol efficacies of agents against blue and green mould and anthracnose in citrus fruit.
  
  
  RESULTS
  Based on the screening assays of saccharides and antioxidants, response surface methodology was used to optimize sucrose, sodium glutamate and skim milk to improve viability of freeze-dried Pi. membranifaciens. Biocontrol assays were conducted between fresh and freeze-dried Pi. membranifaciens against Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides in citrus fruit. Solving the regression equation indicated that the optimal protective medium was 6·06% (w/v) sucrose combined with 3·40% (w/v) sodium glutamate and 5·43% (w/v) skim milk. Pi. membranifaciens freeze-dried in the optimal protective medium showed 76·80% viability, and retained biocontrol efficacy against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit.
  
  
  CONCLUSIONS
  The optimal protective medium showed more effective protective properties than each of the three protectants used alone. The viability of freeze-dried Pi. membranifaciens finally reached 76·80%. Meanwhile, the biocontrol efficacies showed no significant difference between fresh and freeze-dried yeast against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit.
  
  
  CONCLUSIONS
  The results showed the potential value of Pi. membranifaciens CICC 32259 for commercialization.
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.
authors.forename: X
authors.initials: X
authors.lastname: Niu
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.|Chongqing Special Food Programme and Technology Research Center, Chongqing, China.
authors.forename: L
authors.initials: L
authors.lastname: Deng
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.|Chongqing Special Food Programme and Technology Research Center, Chongqing, China.
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.|Chongqing Special Food Programme and Technology Research Center, Chongqing, China.
authors.forename: S
authors.initials: S
authors.lastname: Yao
authors.affiliation: College of Food Science, Southwest University, Chongqing, China.|Chongqing Special Food Programme and Technology Research Center, Chongqing, China.
authors.forename: K
authors.initials: K
authors.lastname: Zeng
mesh_terms: D002957:Citrus / Q000382:microbiology*; D020231:Colletotrichum / Q000502:physiology; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism*; D005612:Freeze Drying; D005638:Fruit / Q000737:chemistry / Q000382:microbiology; D010407:Penicillium / Q000502:physiology; D010843:Pichia / Q000737:chemistry / Q000254:growth & development / Q000502:physiology*; D010935:Plant Diseases / Q000469:parasitology / Q000517:prevention & control; D011309:Preservation, Biological / Q000295:instrumentation / Q000379:methods*; D013395:Sucrose / Q000378:metabolism
chemical_list: D003470:Culture Media; D013395:Sucrose
keywords: Pichia membranifaciens; biocontrol efficacy; citrus fruit; freeze-drying; protective medium; response surface methodology