Polyhydroxyalkanoate Production by Gordonia lacunae BS2T in Hydrolysates of Canola FinesS

Microbial polyhydroxyalkanoates (PHAs) are biodegradable biopolymers that are gaining traction as replacements for conventional petroleum-based plastics. In this study, sugar utilization, growth and polyhydroxybutyrate (PHB) and polyhdroxyvalerate (PHV) production in synthetic and real hydrolysates of Canola fines (SHCF, RHCF) by Gordonia lacunae BS2T were evaluated: (i) in SHCF under different C:N ratios and O2 availability, and (ii) in SHCF and RHCF (50% and 100%) under shaking v/s static conditions with limited or non-limited O2. The bacterium was able to utilize glucose, cellobiose, arabinose, and xylose. Athough O2 limitation reduced growth, higher measured concentrations of 3-hydroxyvalerate (3HV) were achieved under O2 limitation, translating into slightly higher 3-hydroxybutyrate (3HB)+3HV yields (15.4 ± 2.36 %wt.wt.) than under non-O2 limited conditions (12.4 ± 2.26 %wt.wt.). Notably, 50% RHCF was the most suitable medium for growth and PHB+PHV production, while 100% RHCF was the least suitable. The 3HV+3PV concentration (0.35 g/L), 3HV fraction (24%), and yield (15.4 %wt.wt.) in 50% RHCF were highest under static, O2-limited conditions, corresponding with negligible sugar utilization (1.6 mg/day.100 mL−1 glucose) and suggesting alternative metabolic pathways using other substrates in the RHCF for growth. Nuclear magnetic resonance results indicated that Gordonia lacunae BS2T produces a desirable co-polymer (PHBV), paving the way for ongoing research using this bacterium.