with FAN and IP consumption. The next phase begins after complete
IP consumption that initiates PHB formation. Therefore, PHB
accumulation occurs due to phosphorus limitation. The glycerol to
PHB conversion yield is 0.47 g g−1 that is significantly higher than
other studies ranging from 0.22 g g−1 to 0.37 g g−1 (Cavalheiro et al.,
2009; Ibrahim and Steinbuchel 2009; Hermann-Krauss et al., 2013;
Kachrimanidou et al., 2014). The high yield should be attributed
to the consumption of other carbon sources that may have been
produced during SFM fractionation. The productivity obtained in
the present study was 0.4 g L−1 h−1, while the highest PHB concentration
was 57 g L−1 with an intracellular content of 86.2% (w/w).
These results are among the highest achieved from media based
on crude glycerol. Hermann-Krauss et al. (2013) reported an intracellular
PHA content of 75.4% and a volumetric productivity of
0.12 g L−1 h−1. The efficiency of hydrolysate III for PHB production
could be attributed to optimum balance of nutrients in the medium.
Optimum resource utilization, process integration and biomass
refining lead to efficient separation of value-added products from
SFM and PHB production from remaining streams.