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Fig. 1 | BMC Microbiology

Fig. 1

From: Lactobacillus rhamnosus GG modifies the metabolome of pathobionts in gnotobiotic mice

Fig. 1

Comparison of different LC-MS normalization procedures. a Mice were fed for 9 weeks, and feces were sampled in weeks 0, 4, 5, 6, 7, 8 and 9. Mice remained germ-free (GF) throughout. Equal volumes of extraction buffer were added to all fecal samples regardless of the fecal weight. After LC-MS analysis, the data either remained non-normalized, or were normalized to fecal weight (Post-LC-MS). b PCA analysis of the non-normalized (to fecal weight) LC-MS metabolite data. c PCA analysis of the LC-MS metabolite data normalized to fecal weight. d Feces of GF mice were collected three times over two weeks. Prior to LC-MS analysis, they were weighed and the volume of the extraction buffer was adjusted to correspond to the weight of the feces (Pre-LC-MS). e PCA analysis of the fecal metabolites in GF mice used in (d). f Density plot of the CV (coefficient of variation) under different normalization conditions: non-normalized, post-LC-MS normalized, and pre-LC-MS normalized. g Heatmap of non-normalized LC-MS analysis of fecal metabolites from (a). h Heatmap of post-LC-MS-normalized data of fecal metabolites from (a). i Heatmap of pre-LC-MS normalized data of fecal metabolites from (d)

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