TABLE 1.
Comparison of growth and PHA production during all cultivations.
| Biomass accumulation stage |
PHA production stage |
Overall |
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| CDW (g L–1) | PHB (wt%) | NH3 (mM) | Duration (h) | CDW (g L–1) | P(HB-co-HHx) (wt%) | HHx (mol%) | STY (g L–1 h–1) | |
| Two-stage fed-batch | 35.8 ± 1.2 | 9.3 ± 0.8 | 29.7 ± 15.3 | 39 | 124.0 ± 5.6 | 86.1 ± 3.1 | 16.9 ± 0.2 | 1.22 |
| Repeated fed-batch 1st cycle | 31.1 ± 6.7 | 14.3 ± 0.8 | 45.4 ± 3.6 | 36 | 118.9 ± 2.1 | 82.9 ± 11.5 | 18.1 ± 0.9 | 1.23 |
| Repeated fed-batch 2nd cycle | 27.9 ± 1.9 | 19.4 ± 2.0 | 137.3 ± 28.6 | 24 | 35.8 ± 10.1 | 33.9 ± 29.2 | 20.6 ± 2.4 | 0.18* |
| Repeated fed-batch 3rd cycle | 23.9 ± 6.7 | 19.1 ± 1.1 | 70.4 ± 19.3 | 26 | 53.6 ± 18.7 | 56.3 ± 18.4 | 13.5 ± 2.3 | 0.43* |
CDW and PHA concentrations, including HHx content for the production stage, where P(HB-co-HHx) was synthesized, are displayed. In addition, final PHA STYs are shown for each run. NH3 accumulation at the end of the biomass accumulation stage is presented in order to understand the low polymer yields(∗) attained in the 2nd and the 3rd cycle of the repeated fed-batch. In addition, the duration of the biomass accumulation stage shows the advantage of the repeated fed-batch approach. Measurements represent means from duplicate cultivations ± are indicating minimum and maximum values.