title: Optimization of physical parameters for exo-biopolymer production in submerged mycelial cultures of two entomopathogenic fungi Paecilomyces japonica and Paecilomyces tenuipes.
abstract: OBJECTIVE
  In the present study, two different optimization techniques were used to determine the suitable operating parameters for exo-biopolymer production in submerged mycelial cultures of two entomopathogenic fungi Paecilomyces japonica and Paecilomyces tenuipes.
  
  
  RESULTS
  First, the rotating simplex method, a nonstatistical optimization technique, was employed to obtain the best combination of physical parameters (viz. pH, agitation intensity, aeration rate) for maximum exo-biopolymer production by P. japonica in a batch bioreactor. The optimal combination was determined to be a pH of 8.06, an aeration of 3 vvm, without any impeller agitation, producing a 17-time increase in exopolymer production (34.5 g l(-1)) when compared with that achieved in unoptimized flask cultures. Second, the uniform design method, a statistical optimization technique, was employed to determine the best operating parameters for submerged culture of P. tenuipes. The optimal combination for mycelial growth was determined to be a pH of 4.88, an aeration of 2 vvm and an agitation of 350 rpm, while a pH of 4, an aeration of 2 vvm and an agitation of 150 rpm was best for exo-biopolymer production.
  
  
  CONCLUSIONS
  The exo-biopolymer production in P. japonica optimized by the rotating simplex method was strikingly improved (max. 34.5 g l(-1)), and the exo-biopolymer production in P. tenuipes optimized by the uniform design method was also significantly increased (max. 3.4 g l(-1)).
  
  
  CONCLUSIONS
  The successful application of these two different optimization techniques in this study implies that these methods are worthy of applying to other fermentation systems for the production of bioactive mycelial biomass and exo-biopolymers in liquid culture of higher fungi.
authors.affiliation: Department of Biotechnology, Daegu University, Kyungbuk, Korea.
authors.forename: Chun Ping
authors.initials: CP
authors.lastname: Xu
authors.forename: Jayanta
authors.initials: J
authors.lastname: Sinha
authors.forename: Jun Tae
authors.initials: JT
authors.lastname: Bae
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Kim
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Yun
mesh_terms: D018533:Biomass; D001704:Biopolymers / Q000096:biosynthesis*; D003470:Culture Media / Q000737:chemistry; D005947:Glucose / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008320:Maltose / Q000032:analysis; D025282:Mycelium / Q000254:growth & development / Q000378:metabolism; D010143:Paecilomyces / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D003470:Culture Media; D008320:Maltose; D005947:Glucose