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. 2009 Sep 23;4(9):e7125.
doi: 10.1371/journal.pone.0007125.

Monitoring bacterial community of human gut microbiota reveals an increase in Lactobacillus in obese patients and Methanogens in anorexic patients

Fabrice Armougom  1 , Mireille Henry, Bernard Vialettes, Denis Raccah, Didier Raoult
Affiliations

Monitoring bacterial community of human gut microbiota reveals an increase in Lactobacillus in obese patients and Methanogens in anorexic patients

Fabrice Armougom et al. PLoS One. .

Abstract

Background: Studies of the bacterial communities of the gut microbiota have revealed a shift in the ratio of Firmicutes and Bacteroidetes in obese patients. Determining the variations of microbial communities in feces may be beneficial for the identification of specific profiles in patients with abnormal weights. The roles of the archaeon Methanobrevibacter smithii and Lactobacillus species have not been described in these studies.

Methods and findings: We developed an efficient and robust real-time PCR tool that includes a plasmid-based internal control and allows for quantification of the bacterial divisions Bacteroidetes, Firmicutes, and Lactobacillus as well as the methanogen M. smithii. We applied this technique to the feces of 20 obese subjects, 9 patients with anorexia nervosa, and 20 normal-weight healthy controls. Our results confirmed a reduction in the Bacteroidetes community in obese patients (p<0.01). We found a significantly higher Lactobacillus species concentration in obese patients than in lean controls (p=0.0197) or anorexic patients (p=0.0332). The M. smithii concentration was much higher in anorexic patients than in the lean population (p=0.0171).

Conclusions: Lactobacillus species are widely used as growth promoters in the farm industry and are now linked to obesity in humans. The study of the bacterial flora in anorexic patients revealed an increase in M. smithii. This increase might represent an adaptive use of nutrients in this population.

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Conflict of interest statement

Competing Interests: The « Université de la Mediterranée » deposed a patent on this study for which the authors Armougom F., Henry M., Drancourt M., and Raoult D. are the inventors.

Figures

Figure 1
Figure 1. Firmicutes system sensitivity at genus taxonomic level.
Scores in parentheses indicate the number of sequences matching the system out of the total sequence number of a given genus.
Figure 2
Figure 2. Bacteroidetes system sensitivity at genus taxonomic level.
Scores in parentheses indicate the number of sequences matching the system out of the total sequence number of a given genus.
Figure 3
Figure 3. The Bacteroidetes quantification.
Box and whisker: 10–90 percentiles. Outliers are plotted as a black bubble, means are plotted as a plus, and medians are the black lines in the boxes. P value <0.05 is represented as * and P value <0.01 is represented as ** on the graph.
Figure 4
Figure 4. Distribution of high Lactobacillus concentrations.
The number of individuals having a high Lactobacillus concentration was 1 out of 20, 8 out of 20, and 0 out of 9 for the lean, obese, and anorexic groups, respectively.
Figure 5
Figure 5. Quantification of the archaeon M. smithii species.
Values are means±SD. P value <0.05 is represented as * and P value > 0.05 is indicated by “ns” for not significant.
See this image and copyright information in PMC

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