Earticle

초록

영어

Lignin hydrolysates are a potential source of sugar for the renewable production of biofuels by fermentative bacterial strains. However, when the lignin-cellulose is hydrolyzed, many phenolic acids and aldehydes are produced, including coumaric acid, ferulic acid and vanillin. Microarray results obtained with a culture of E. coli exposed to ferulic acid found that several gene clusters were strongly induced, including the marA regulon and the aaeXAB operon. Using these findings, the promoters from several genes included in the marA regulon were cloned upstream of the luxCDABE genes within plasmid pDEW201, allowing us to monitor the expression levels of each gene through the bioluminescent output. Two strains were used to monitor for the presence of the hydrolysate compounds, ZWF, which has the zwf promoter fused with the lux operon, and SP4, which has the inaA promoter fused with the lux operon. Tests with ferulic acid found strain SP4 to be more responsive, with a greater induction level than ZWF. These results are in agreement with the microarray data which showed the inaA gene was induced by ferulic acid while zwf showed no significant change. Another interesting finding of this study was the stronger induction of the inaA promoter, i.e., strain SP4, by the acid forms of the test compounds when compared with the aldehyde forms. For instance, when SP4 was exposed to the 1g/L of vanillic acid or vanillin, the acid resulted in a 30-fold induction while the aldehyde gave only a 5-fold induction. Finally, a comparison between several phenolic acids showed that strain SP4 responded differentially to non-native compounds. In other words, a test with 1 g/L 4-hydrobenzoic acid, a phenolic acid produced naturally by E. coli, resulted in only a 3-fold induction while both vanillic and ferulic acid led to a 30-fold induction when added at the same concentration. In this study it was demonstrated that strain SP4 “responds” to compounds present within hydrolysates and that this strain shows a preferential response 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 present in the hydrolysate.

키워드

저자

• Robert MITCHELL [ School of Nano biotechnology and Chemical Engineering, UNIST, Ulsan, 689-798. ]
• Siseon LEE [ School of Nano biotechnology and Chemical Engineering, UNIST, Ulsan, 689-798. ]

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간행물

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• 간행물명

  한국생물공학회 학술대회

• 간기

  반년간

• 수록기간

  1985~2013

• 십진분류

  KDC 476 DDC 576