Fig. 2From: Omics-based analyses revealed metabolic responses of Clostridium acetobutylicum to lignocellulose-derived inhibitors furfural, formic acid and phenol stress for butanol fermentationHeat map analysis of the intracellular metabolome. Relative abundances of intracellular metabolites are processed by zero-mean normalization. All the metabolites are ordered by hierarchical cluster analysis. Suffixes _1, _2, _3 and _4 stand for the sampling time of 15 h, 18 h, 24 h and 36 hBack to article page