High-Cell-Density cultivation of pseudomonas putida IPT 046 and medium-chain-length polyhydroxyalkanoate production from sugarcane carbohydrates |
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Authors: | Simone Cardoso Diniz Marilda Keico Taciro José Gregório Cabrera Gomez José Geraldo da Cruz Pradella |
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Institution: | 1. Biotechnology Group, Division of Chemistry, Institute for Technological Research of S?o Paulo State-IPT, Av. Professor Almeida Prado, 532, CEP 05508-901, S?o Paulo, S.P., Brazil
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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 0.65h−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·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. |
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Keywords: | Polyhydroxyalkanoate Pseudomonas putida high cell-density sugarcane kinetics studies |
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