Department of Microbiology, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan; Department of Analytical Biochemistry, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo, 204-8588, Japan.
Department of Microbiology, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan.
Biochem Biophys Res Commun. 2022 Jan 15;588:104-110. doi: 10.1016/j.bbrc.2021.12.053. Epub 2021 Dec 17.
Many species of bacteria interact on the human skin to form a certain microbiome. Delftia acidovorans, a bacterium detected from human skin, inhibits the growth of S. epidermidis, a dominant bacterium of the human skin microbiota. Here, we show that ammonia secreted by D. acidovorans inhibits the growth of S. epidermidis by increasing the pH value of the medium. The pH value of D. acidovorans culture supernatant (CS) was higher than that of the medium without culture. The inhibitory activity of the D. acidovorans CS against the growth of S. epidermidis was decreased by neutralization with hydrochloric acid. Genes encoding enzymes related to ammonia production were found in the D. acidovorans genome. Moreover, the D. acidovorans CS contained a high concentration of ammonia. The addition of ammonia to S. epidermidis culture led to an increase in the reactive oxygen species (ROS) production and inhibited S. epidermidis growth. The addition of sodium hydroxide also led to an increase in the ROS production and inhibited S. epidermidis growth. The inhibitory activity of ammonia and sodium hydroxide against S. epidermidis growth was suppressed by malonic acid, an inhibitor of succinate dehydrogenase in the tricarboxylic acid (TCA) cycle, and N-acetyl-l-cysteine, a free radical scavenger. These findings suggest that D. acidovorans secretes ammonia and alkaline stress inhibits the growth of S. epidermidis by inducing TCA cycle-triggered ROS production.
许多细菌在人类皮肤上相互作用形成特定的微生物组。从人体皮肤中检测到的德氏菌属（Delftia）能够抑制表皮葡萄球菌（一种人类皮肤微生物组中的优势菌）的生长。在这里，我们发现德氏菌属分泌的氨通过增加培养基的 pH 值来抑制表皮葡萄球菌的生长。德氏菌属培养上清液（CS）的 pH 值高于无培养物的培养基。用盐酸中和可降低德氏菌属 CS 对表皮葡萄球菌生长的抑制活性。在德氏菌属基因组中发现了编码与氨生成相关的酶的基因。此外，德氏菌属 CS 中含有高浓度的氨。向表皮葡萄球菌培养物中添加氨会导致活性氧（ROS）的产生增加，从而抑制表皮葡萄球菌的生长。添加氢氧化钠也会导致 ROS 产生增加并抑制表皮葡萄球菌的生长。琥珀酸脱氢酶抑制剂丙二酸和自由基清除剂 N-乙酰-l-半胱氨酸可抑制氨和氢氧化钠对表皮葡萄球菌生长的抑制活性。这些发现表明，德氏菌属分泌氨，碱性应激通过诱导三羧酸（TCA）循环触发的 ROS 产生来抑制表皮葡萄球菌的生长。
