The current study involved carrying out adaptive evolution to inculcate
tolerance to hydrolysate-derived aldehyde-based inhibitors, furfural,
vanillin, syringaldehyde and 4-hydroxybenzaldehyde (4-HB) for the
valorization of pretreated lignocellulosic biomass.
Methodology: The growth-inhibitory effects of the aforementioned
inhibitors on E. coli MG1655 were investigated. The percentage of
inhibition was calculated from the initial growth, followed by extrapolating
the IC50 values for each inhibitor. Based on these findings,
adaptation experiments were conducted for individual inhibitors at a
concentration lesser than or closer to IC50.
The specific growth rate of cells was lowered by 2.2-, 3-, 1.3- and 5- fold
when grown in the presence of furfural, vanillin, syringaldehyde and 4-
hydroxybenzaldehyde (4-HB), respectively. The adapted strains which were
grown in the presence of furfural (9mM), vanillin (9mM), syringaldehyde (8mM)
and 4- HB (6mM) individually showed around 1.5 -2.5- fold increase in the
specific growth rate as compared to the wild-type with decreased lag phases
and increased final cell densities.
Interpretation: The strains, subjected to adaptive
evolution, resulted in increased tolerance to single inhibitors and these
will further be sequentially adapted to other three inhibitors for their
utilization in the valorization of pretreated lignocellulosic biomass.
Adaptive evolution, Aldehyde- based inhibitors, E. coli, Inhibitor
tolerance, Specific growth rate