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Appl Environ Microbiol. 1991 March; 57(3): 625-629
Copyright © 1991, American Society for Microbiology. All Rights Reserved.

Continuous Production of Long-Side-Chain Poly-ß-Hydroxyalkanoates by Pseudomonas oleovorans

¹ Department of Chemical Engineering, Ecole Polytechnique de Montréal, C.P. 6079, Succursale "A," Montreal, Quebec H3C 3A7, and Chemistry Department, McGill University, Montreal, Quebec H3A 2A7, ² Canada

ABSTRACT

Shake flask experiments showed that Pseudomonas oleovorans began to be growth inhibited at 4.65 g of sodium octanoate liter^-1, with total inhibition at 6 g liter^-1. In chemostat studies with 2 g of ammonium sulfate and 8 g of octanoate liter^-1 in the feed, the maximum specific growth rate was 0.51 h^-1, and the maximum specific rate of poly-ß-hydroxyalkanoate (PHA) production was 0.074 g of PHA g of cellular protein^-1 h^-1 at a dilution rate (D) of 0.25 h^-1. When the specific growth rate (µ) was <0.3 h^-1, the PHA composition was relatively constant with a C₄/C₆/C₈/C₁₀ ratio of 0.1:1.7:20.7:1.0. At µ > 0.3 h^-1, a decrease in the percentage of C₈ with a concomitant increase in C₁₀ monomers as µ increased was probably due to the effects of higher concentrations of unmetabolized octanoate in the fermentor. At D = 0.24 h^-1 and an increasing carbon/nitrogen ratio, the percentage of PHA in the biomass was constant at 13% (wt/wt), indicating that nitrogen limitation did not affect PHA accumulation. Under carbon-limited conditions, the yield of biomass from substrate was 0.76 g of biomass g of octanoate^-1 consumed, the yield of PHA was 0.085 g of PHA g of octanoate^-1 used, and 7.9 g of octanoate was consumed for each gram of NH₄⁺ supplied. The maintenance coefficient was 0.046 g of octanoate g of biomass^-1 h^-1. Replacement of sodium octanoate with octanoic acid appeared to result in transport-limited growth due to the water insolubility of the acid.

^* Corresponding author.

This article has been cited by other articles:

• Durner, R., Witholt, B., Egli, T. (2000). Accumulation of Poly[(R)-3-Hydroxyalkanoates] in Pseudomonas oleovorans during Growth with Octanoate in Continuous Culture at Different Dilution Rates. Appl. Environ. Microbiol. 66: 3408-3414 [Abstract] [Full Text]  
• Madison, L. L., Huisman, G. W. (1999). Metabolic Engineering of Poly(3-Hydroxyalkanoates): From DNA to Plastic. Microbiol. Mol. Biol. Rev. 63: 21-53 [Abstract] [Full Text]