Ling Jun, Zhou Lan, Wu Guichun, Zhao Yancun, Jiang Tianping, Liu Fengquan
Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
Academy of Agricultural Sciences of Yanbian, Longjing, China.
Front Microbiol. 2019 Dec 3;10:2748. doi: 10.3389/fmicb.2019.02748. eCollection 2019.
species are emerging as novel sources of antibiotics, but the regulation of their physiological metabolism is still poorly understood. In this work, we extracted AHL (acyl-homoserine lactone) autoinducers, identified the structures of AHLs and described the AHL quorum-sensing system in OH23. AHLs were isolated from the supernatant of OH23, and ESI-MS/MS (electrospray ionization mass spectrometry) analysis revealed biosynthesis of three different AHL chemical structures by OH23: -(3-oxohexanoyl)- homoserine lactone (HSL), 3-OH-C-HSL and C-HSL. The growth rate of AHL quorum-sensing knockout mutants was dramatically increased compared to that of wildtype. Sucrose consumptions were also twice as high in AHL quorum-sensing knockout mutants than that in wildtype in early-log phase. Additionally, expression of key genes related to sucrose metabolism α-glucosidase was enhanced in AHL quorum-sensing knockout mutants, which indicated that AHL quorum sensing negatively regulates sucrose uptake and metabolism which further affects the growth rate of . Furthermore, autolysis was strongly induced in AHL quorum-sensing knockout mutants compared to wildtype, suggesting that AHL quorum sensing plays a negative regulatory role in cell autolysis. Moreover, compared to wildtype, XSAC (-specific antibiotic compound) production was significantly increased in AHL knockout mutants in the early-log and late-log phases, and surface motility capabilities are also enhanced also in AHL knockout mutants; the normalized data of XSAC production and surface motility and expressions of key genes related to these two phenotypes reveal that growth rare and autolysis strongly affects XSAC biosynthesis and surface motility rather than AHL quorum-sensing system. Our results show that the AHL quorum-sensing system negatively regulates cell growth and autolysis, and further maintain nutrition homeostasis and population stability in .
物种正成为抗生素的新来源，但其生理代谢的调控仍知之甚少。在这项工作中，我们提取了AHL（酰基高丝氨酸内酯）自诱导物，鉴定了AHL的结构，并描述了OH23中的AHL群体感应系统。从OH23的上清液中分离出AHL，电喷雾电离质谱（ESI-MS/MS）分析显示OH23生物合成了三种不同的AHL化学结构：-(3-氧代己酰基)-高丝氨酸内酯（HSL）、3-OH-C-HSL和C-HSL。与野生型相比，AHL群体感应敲除突变体的生长速率显著提高。在对数早期，AHL群体感应敲除突变体的蔗糖消耗量也比野生型高两倍。此外，AHL群体感应敲除突变体中与蔗糖代谢α-葡萄糖苷酶相关的关键基因表达增强，这表明AHL群体感应负调控蔗糖摄取和代谢，进而影响其生长速率。此外，与野生型相比，AHL群体感应敲除突变体中自溶被强烈诱导，表明AHL群体感应在细胞自溶中起负调控作用。此外，与野生型相比，AHL敲除突变体在对数早期和晚期的XSAC（特异性抗生素化合物）产量显著增加，AHL敲除突变体的表面运动能力也增强；XSAC产量和表面运动的标准化数据以及与这两种表型相关的关键基因表达表明，生长速率和自溶强烈影响XSAC生物合成和表面运动，而不是AHL群体感应系统。我们的结果表明，AHL群体感应系统负调控细胞生长和自溶，并进一步维持其营养稳态和群体稳定性。
