Sakanaka Mikiyasu, Sugiyama Yuta, Nara Misaki, Kitakata Aya, Kurihara Shin
Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan.
FEMS Microbiol Lett. 2018 Feb 1;365(4). doi: 10.1093/femsle/fny003.
Polyamine concentrations in the intestine are regulated by their biosynthesis by hundreds of gut microbial species and these polyamines are involved in host health and disease. However, polyamine biosynthesis has not been sufficiently analyzed in major members of the human gut microbiota, possibly owing to a lack of gene manipulation systems. In this study, we successfully performed markerless gene deletion in Bacteroides dorei, one of the major members of the human gut microbiota. The combination of a thymidine kinase gene (tdk) deletion mutant and a counter-selection marker tdk, which has been applied in other Bacteroides species, was used for the markerless gene deletion. Deletion of tdk in B. dorei caused 5-fluoro-2΄-deoxyuridine resistance, suggesting the utility of B. dorei Δtdk as the host for future markerless gene deletions. Compared to parental strains, an arginine decarboxylase gene (speA) deletion mutant generated in this system showed a severe growth defect and decreased concentration of spermidine in the cells and culture supernatant. Collectively, our results indicate the accessibility of gene deletion and the important role of speA in polyamine biosynthesis in B. dorei.
肠道中的多胺浓度由数百种肠道微生物的生物合成所调节，并且这些多胺与宿主健康和疾病有关。然而，由于缺乏基因操作体系，人类肠道微生物群的主要成员中的多胺生物合成尚未得到充分分析。在本研究中，我们成功地在多氏拟杆菌（人类肠道微生物群的主要成员之一）中进行了无标记基因缺失。已应用于其他拟杆菌属物种的胸苷激酶基因（tdk）缺失突变体和反选择标记tdk的组合用于无标记基因缺失。多氏拟杆菌中tdk的缺失导致对5-氟-2'-脱氧尿苷产生抗性，这表明多氏拟杆菌Δtdk作为未来无标记基因缺失的宿主具有实用性。与亲本菌株相比，在该系统中产生的精氨酸脱羧酶基因（speA）缺失突变体表现出严重的生长缺陷，并且细胞和培养上清液中的亚精胺浓度降低。总的来说，我们的结果表明基因缺失的可及性以及speA在多氏拟杆菌多胺生物合成中的重要作用。
