earticle

영어

In this study, it was demonstrated that E. coli responds to compounds present within hydrolysates through the higher expression of the marA regulon and aaeXAB operon by RT-qPCR with pure hydrolysate compounds, including coumaric acid and vanillin. Using gene fusions of two marA-regulated genes, i.e., inaA and zwf, with the luxCDABE genes in plasmid pDEW201, it was demonstrated that both of these genes are induced by the compounds but that strain SP4 (inaA::lux) is more responsive. Furthermore, it was found that this strain responds preferentially for phenolic acids not naturally produced by E. coli.
These results clearly show the potential of this strain as a biosensor to monitor the characteristics of the wood hydrolysate and to evaluate the possible inhibition of fermentative bacterial strains by the phenolics in the hydrolysate. Finally, tests with an actual hydrolysate, using RT-qPCR, found that the marA regulon was still strongly induced while the expression of the aaeXAB operon was not as significant when compared with the pure chemicals. Based upon the characteristics of both systems, it is assumed that non-phenolics produced during the hydrolysis, including furfural, are involved in the toxicity and that these lead to an induction of the marA regulon but not the aaeXAB operon.