2.5. Effect of wood vinegar (WV) on ALA production by PNSB
in optimized RSW
After the optimum conditions were determined, verified and
shown to be the same for each of the PNSB; these optimal conditions
obtained from a previous experiment were used to
study the effect of WV as a cheap source of levulinic acid on
ALA production in each optimized RSW. Based on our preliminary
work, varying concentrations of WV at 0.00%,
0.31%, 0.63%, 1.25% and 2.50% (v/v) were fed to the PNSB
when they were in their mid log phase of growth in order to
provide levulinic acid to suppress the activity of ALAD and
increase ALA levels (Chung et al., 2005). The parameters for
monitoring were determined after 72 h incubation in the same
way as for the previous experiment. The compositions of WV
including levulinic acid content was determined by HP 6890