Division of Infectious Diseases, Nitte University Centre for Science Education and Research, Nitte (Deemed to be University), Deralakatte, Mangaluru 575018, Karnataka, India.
Nitte (Deemed to be University), University Enclave, Medical Sciences Complex, Deralakatte, Mangaluru 575018, Karnataka, India.
Can J Microbiol. 2019 Sep;65(9):681-690. doi: 10.1139/cjm-2018-0700. Epub 2019 May 10.
Gastric acidity is one of the earliest host defences faced by ingested organisms, and successful pathogens need to overcome this hurdle. The objective of this study was the systematic assessment of acid-stress response of isolated from coastal regions of Mangaluru. Acid-shock experiments were carried out at pH 4.0 and pH 4.5, with different experimental conditions expected to produce a varied acid response. Exposure to mild acid before the acid shock was favourable to the bacteria but was dependent on cell population and pH of the media and was independent of the strains tested. Lysine-dependent acid response was demonstrated with reference to the previously identified lysine decarboxylase system. Additionally, the results showed that inoculation into oysters provided some level of protection against acid stress. Increased expression of lysine/cadaverine genes was observed upon the addition of ground oyster and was confirmed by quantitative real-time PCR. The potential role of ornithine was analyzed with regard to acid stress, but no change in the survival pattern was observed. These findings highlight the physiology of bacteria in acid stress.
胃酸是摄入的生物体最早面临的宿主防御之一，而成功的病原体需要克服这一障碍。本研究的目的是系统评估从芒格洛尔沿海地区分离的 对酸应激的反应。在 pH 值为 4.0 和 4.5 时进行酸休克实验，不同的实验条件预计会产生不同的酸反应。在酸休克之前暴露于弱酸对细菌有利，但取决于细胞群体和培养基的 pH 值，且与测试的菌株无关。赖氨酸依赖的酸反应与先前鉴定的赖氨酸脱羧酶系统有关。此外，结果表明，接种到牡蛎中可以提供一定程度的酸应激保护。加入磨碎的牡蛎后，观察到赖氨酸/尸胺基因的表达增加，并通过定量实时 PCR 得到证实。分析了鸟氨酸在酸应激中的潜在作用，但未观察到存活模式的变化。这些发现强调了细菌在酸应激中的生理学。
