Affiliation:
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-β-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 C
4
/C
6
/C
8
/C
10
ratio of 0.1:1.7:20.7:1.0. At μ > 0.3 h
-1
, a decrease in the percentage of C
8
with a concomitant increase in C
10
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 NH
4
+
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.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
67 articles.
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