Project description:Background. Food can affect the microbial balance in the human intestine, and the ingestion of probiotics may play a role in the current obesity pandemic. The objective of our study was to determine if increased Lactobacillus spp. in the intestinal microflora of mice can promote growth and if changes in the intestinal microflora are associated with modifications in metabolism. Methodology. Female BALBc mice were divided between one control and two experimental groups and inoculated either once or twice with 4×1010 Lactobacillus per animal in PBS or with PBS alone. Fecal samples were collected and tested using qPCR to detect and quantify Lactobacillus spp., Bacteroidetes and Firmicutes. Gene expression by microarray and RT-PCR was studied in liver and adipose tissue. Finally, metabolic parameters in the plasma were tested. Principal Findings. In three independent experiments, we observed an increase in both weight gain and liver weight in mice inoculated with 4×1010 Lactobacillus. Inoculation with Lactobacillus sp. (ostrich) increased the Lactobacillus spp. and Firmicutes DNA copy number in feces. The transcriptional profile of liver tissue from mice inoculated with Lactobacillus sp. (ostrich) was enriched for Gene Ontology terms related to the immune response and metabolic modifications. The mRNA levels of fatty acyl synthase (Fas), sterol regulatory element binding factor 1 (Srebp1c), tumor necrosis factor alpha (Tnf), cytochrome P450 2E1 (Cyp2e1) and 3-phosphoinositide-dependent protein kinase-1 (Pdpk1) were significantly elevated in liver tissue in experimental group animals. In gonadal adipose tissue, the expression of leptin, peroxisome proliferator-activated receptor gamma (Pparg and Srebp1c was significantly higher in experimental group animals, whereas the expression of adiponectin was significantly lower. Conclusions. Alterations in the intestinal microbiota resulted in increased weight gain. Furthermore, increased Lactobacillus spp. in the intestinal microflora of mice inoculated with Lactobacillus sp. (ostrich) resulted in accelerated weight gain, liver enlargement and metabolic changes in the plasma, liver and adipose tissue.
