The mixture was boiled at 100 C for 1 h to
hydrolyze PHB polymer into crotonic acid. Before analysis by HPLC,
the sample was 25-fold diluted with water and filtered through a
0.45 lm polypropylene membrane filter to remove cell debris.
HPLC analysis was performed by 10 lL of sample injection, isocratic
solvent system was run at 70% (v/v) of 10 mM phosphate
buffer pH 2.3 and 30% (v/v) of acetonitrile with a flow rate of
1.0 mL/min.