16S rRNA gene sequencing (human GM). 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.

人体肠道菌群（human gut microbiota）与肥胖及其相关代谢并发症（如心血管疾病）密切相关。血清三酰甘油（triacylglycerol, TAG）浓度升高会增加心血管疾病的发病风险。本研究依托一项为期4周的平行人体干预试验，发现对40名健康青年受试者补充副干酪乳杆菌副干酪亚种（Lactobacillus paracasei subsp. paracasei）L. casei W8（以下简称W8），持续4周后可降低其血清三酰甘油浓度，该效应可能与硬脂酰辅酶A去饱和酶1（stearoyl-CoA desaturase-1, SCD1）活性降低有关。本研究旨在探究W8在每日剂量为10^10菌落形成单位（colony-forming unit, CFU）的4周补充后，在人体肠道的定植能力，以及补充终止2周后是否仍存在菌株增殖现象。此外，本研究还探究了W8摄入对肠道菌群（gut microbiota, GM）组成的影响，以及上述菌群变化是否与此前报道的血清三酰甘油浓度变化存在关联。研究分别在基线期、4周补充期结束时以及补充终止后2周采集粪便样本。采用实时荧光定量PCR（quantitative real-time polymerase chain reaction, qPCR）检测干酪乳杆菌群成员的相对丰度，同时采用标签编码部分16S rRNA基因焦磷酸测序分析肠道菌群组成。结果显示，经4周W8补充后，受试者肠道菌群中干酪乳杆菌的相对丰度从总菌群的8.48×10^-6%（标准差SD=2.08×10^-5%）显著升高至2.83×10^-3%（标准差SD=4.12×10^-3），差异具有极显著统计学意义（p < 0.001）。补充终止后2周，干酪乳杆菌的相对丰度仍较干预前升高14倍，差异仍具有显著统计学意义（p < 0.01）。2周洗脱期后检测到的干酪乳杆菌丰度与干预前的基线丰度呈正相关，提示W8成功实现肠道定植。但干酪乳杆菌丰度的升高与血清三酰甘油浓度变化及硬脂酰辅酶A去饱和酶1活性变化均无显著相关性。尽管干酪乳杆菌丰度发生了上述变化，但受试者肠道菌群的整体组成并未出现明显改变。