16S rRNA gene sequencing (human GM)

The human gut microbiota has been linked to obesity and its metabolic complications such as cardiovascular disease. The risk of developing cardiovascular disease increases with elevated concentration of serum triacylglycerol (TAG). In a parallel human intervention study of four weeks duration, we found that supplementation with Lactobacillus paracasei subsp paracasei L. casei W8 (W8) for four weeks reduces the concentration of TAG in 40 young healthy adults. This effect was likely due to decreased stearoyl-CoA desaturase-1 (SCD1) activity. Here we investigate the ability of W8 to colonise the human gut after the four weeks supplementation of W8 (1010 CFU), and whether proliferation two weeks after supplementation was ended occurred. Furthermore, we investigated if consumption of W8 affected the gut microbiota (GM) composition and if these changes were associated with changes in TAG concentrations reported previously. Faecal samples were collected at baseline, after four weeks supplementation and two weeks after the supplementation was endet. qPCR was used to determine the relative abundance of Lactobacillus casei group-members while tag-encoded partial 16S rRNA gene pyrosequencing was used to analyse the GM composition. We found that four weeks supplementation with W8 resulted in an increase in the relative abundance of L. casei from 8.48·10-6 % (SD = 2.08·10-5 %) to 2.83·10-3 % (SD = 4.12·10-3) (p < 0.001) of the total GM. Two weeks after the supplementation ended, the relative abundance of L. casei was still increased 14 times compared to before the intervention (p < 0.01). The abundance of L. casei after the two weeks wash out period was positively correlated with the abundance of L. casei before the consumption began indicating colonisation by W8. The increase in the abundance of L. casei was however not correlated with changes in TAG concentrationor changes in SCD1 activity. Despite the changes observed in L Casei, the overall GM composition was not changed.