title: High-cell-density cultivation of Pseudomonas putida IPT 046 and medium-chain-length polyhydroxyalkanoate production from sugarcane carbohydrates.
abstract: We studied high-density cultures of Pseudomonas putida IPT 046 for the production of medium-chain-length polyhydroxyalkanoates (PHAMCL) using an equimolar mixture of glucose and fructose as carbon sources. Kinetics studies of P. putida growth resulted in a maximum specific growth rate of 0.65 h(-1). Limitation and inhibition owing to NH4+ ions were observed, respectively, at 400 and 3500 mg of NH4+/L. The minimum concentration of dissolved oxygen in the broth must be 15% of saturation. Fed-batch strategies for high-cell-density cultivation were proposed. Pulse feed followed by constant feed produced a cell concentration of 32 g/L in 18 h of fermentation and low PHAMCL content. Constant feed produced a cell concentration of 35 g/L, obtained in 27 h of fermentation, with up to 15% PHAMCL. Exponential feed produced a cell concentration of 30 g/L in 20 h of fermentation and low PHAMCL content. Using the last strategy, 21% PHAMCL was produced during a period of 34 h of fed-batch operation, with a final cell concentration of 40 g/L and NH4+ limitation. Using phosphate limitation, 50 g/L cell concentration, 63% PHAMCL and a productivity of 0.8 g/(L x h) were obtained in 42 h of fed-batch operation. The PHAMCL yield factors from consumed carbohydrate for N-limited and P-limited experiments were, respectively, 0.15 and 0.19 g/g.
authors.affiliation: Biotechnology Group, Division of Chemistry, Institute for Technological Research of São Paulo State-IPT, Av. Professor Almeida Prado, 532, CEP 05508-901, São Paulo, SP, Brazil.
authors.forename: Simone Cardoso
authors.initials: SC
authors.lastname: Diniz
authors.forename: Marilda Keico
authors.initials: MK
authors.lastname: Taciro
authors.forename: José Gregório Cabrera
authors.initials: JG
authors.lastname: Gomez
authors.forename: José Geraldo
authors.initials: JG
authors.lastname: da Cruz Pradella
mesh_terms: D019149:Bioreactors; D002264:Carboxylic Acids / Q000737:chemistry / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods*; D005632:Fructose / Q000378:metabolism*; D005947:Glucose / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D016958:Pseudomonas putida / Q000166:cytology / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D031786:Saccharum / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D010936:Plant Extracts; D000644:Quaternary Ammonium Compounds; D005632:Fructose; D005947:Glucose