作为人类和微生物的生物副产品,甘油对口腔微生物稳态的贡献仍未得到充分研究。在这项研究中,我们检查了血链球菌的甘油代谢,与口腔健康相关的共生。葡萄糖-PTS酶II(manL)的遗传突变体,甘油代谢(glp和dha途径),和转录调节因子的特征是关于甘油分解代谢,增长,过氧化氢(H2O2)的生产,转录,与变形链球菌的竞争。生化测定鉴定glp途径是血链球菌产生H2O2的新来源,与丙酮酸氧化酶(SpxB)无关。遗传分析表明,glp途径需要甘油和转录调节因子,GlpR,表达并受PTS负调控,但不是代谢产物控制蛋白,CcpA.相反,manL或ccpA的缺失增加了spxB的表达,H2O2-不产生甘油的代谢途径(dha),指示与常规碳分解代谢物抑制(CCR)一致的调节模式。在使用浮游和生物膜生长的细胞进行的基于平板的拮抗试验和竞争试验中,甘油极大地改善了血链球菌对变形链球菌的竞争力。glp途径似乎在几种共生链球菌中保守,并在无龋齿的斑块样品中活跃表达。我们的研究表明,甘油代谢在口腔生态中起着比以前理解的更重要的作用。共生链球菌,虽然不能使用甘油作为生长的唯一碳水化合物来源,通过产生ATP和H2O2从甘油的分解代谢中受益。
目的:甘油是口腔中丰富的碳水化合物。然而,关于共生链球菌对甘油的代谢知之甚少,一些最丰富的口腔细菌。这部分是因为大多数链球菌不能在甘油作为唯一碳源上生长。在这项研究中,我们发现血链球菌,与牙齿健康相关的共生,可以通过两种途径降解甘油的持久性和竞争性,其中之一产生的过氧化氢水平能够抑制变形链球菌。初步研究表明,一些额外的共生链球菌也能够分解代谢甘油,和甘油相关基因在人类牙菌斑样品中活跃表达。我们的发现揭示了甘油显着影响微生物稳态的潜力,这值得进一步探索。
As a biological byproduct from both humans and microbes, glycerol\'s contribution to microbial homeostasis in the oral cavity remains understudied. In this study, we examined glycerol metabolism by Streptococcus sanguinis, a commensal associated with oral health. Genetic mutants of glucose-PTS enzyme II (manL), glycerol metabolism (glp and dha pathways), and transcriptional regulators were characterized with regard to glycerol catabolism, growth, production of hydrogen peroxide (H2O2), transcription, and competition with Streptococcus mutans. Biochemical assays identified the glp pathway as a novel source for H2O2 production by S. sanguinis that is independent of pyruvate oxidase (SpxB). Genetic analysis indicated that the glp pathway requires glycerol and a transcriptional regulator, GlpR, for expression and is negatively regulated by PTS, but not the catabolite control protein, CcpA. Conversely, deletion of either manL or ccpA increased the expression of spxB and a second, H2O2-non-producing glycerol metabolic pathway (dha), indicative of a mode of regulation consistent with conventional carbon catabolite repression (CCR). In a plate-based antagonism assay and competition assays performed with planktonic and biofilm-grown cells, glycerol greatly benefited the competitive fitness of S. sanguinis against S. mutans. The glp pathway appears to be conserved in several commensal streptococci and actively expressed in caries-free plaque samples. Our study suggests that glycerol metabolism plays a more significant role in the ecology of the oral cavity than previously understood. Commensal streptococci, though not able to use glycerol as a sole carbohydrate source for growth, benefit from the catabolism of glycerol through production of both ATP and H2O2.
OBJECTIVE: Glycerol is an abundant carbohydrate in the oral cavity. However, little is understood regarding the metabolism of glycerol by commensal streptococci, some of the most abundant oral bacteria. This was in part because most streptococci cannot grow on glycerol as the sole carbon source. In this study, we show that Streptococcus sanguinis, a commensal associated with dental health, can degrade glycerol for persistence and competition through two pathways, one of which generates hydrogen peroxide at levels capable of inhibiting Streptococcus mutans. Preliminary studies suggest that several additional commensal streptococci are also able to catabolize glycerol, and glycerol-related genes are actively expressed in human dental plaque samples. Our findings reveal the potential of glycerol to significantly impact microbial homeostasis, which warrants further exploration.