Jiang Guo-Feng, Jiang Bo-Le, Yang Mei, Liu San, Liu Jiao, Liang Xiao-Xia, Bai Xian-Fang, Tang Dong-Jie, Lu Guang-Tao, He Yong-Qiang, Yu Di-Qiu, Tang Ji-Liang
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan, China. ; Graduate School of Chinese Academy of Sciences, Beijing, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China.
Braz J Microbiol. 2014 Jan 15;44(3):945-52. doi: 10.1590/s1517-83822013000300045. eCollection 2013.
It is well known that the type III secretion system (T3SS) and type III (T3) effectors are essential for the pathogenicity of most bacterial phytopathogens and that the expression of T3SS and T3 effectors is suppressed in rich media but induced in minimal media and plants. To facilitate in-depth studies on T3SS and T3 effectors, it is crucial to establish a medium for T3 effector expression and secretion. Xanthomonas campestris pv. campestris (Xcc) is a model bacterium for studying plant-pathogen interactions. To date no medium for Xcc T3 effector secretion has been defined. Here, we compared four minimal media (MME, MMX, XVM2, and XOM2) which are reported for T3 expression induction in Xanthomonas spp. and found that MME is most efficient for expression and secretion of Xcc T3 effectors. By optimization of carbon and nitrogen sources and pH value based on MME, we established XCM1 medium, which is about 3 times stronger than MME for Xcc T3 effectors secretion. We further optimized the concentration of phosphate, calcium, and magnesium in XCM1 and found that XCM1 with a lower concentration of magnesium (renamed as XCM2) is about 10 times as efficient as XCM1 (meanwhile, about 30 times stronger than MME). Thus, we established an inducing medium XCM2 which is preferred for T3 effector secretion in Xcc.
众所周知，III型分泌系统（T3SS）和III型（T3）效应蛋白对于大多数细菌性植物病原体的致病性至关重要，并且T3SS和T3效应蛋白的表达在丰富培养基中受到抑制，但在基本培养基和植物中被诱导。为了便于对T3SS和T3效应蛋白进行深入研究，建立一种用于T3效应蛋白表达和分泌的培养基至关重要。野油菜黄单胞菌野油菜致病变种（Xcc）是研究植物与病原体相互作用的模式细菌。迄今为止，尚未确定用于Xcc T3效应蛋白分泌的培养基。在此，我们比较了四种据报道可用于诱导黄单胞菌属中T3表达的基本培养基（MME、MMX、XVM2和XOM2），发现MME对于Xcc T3效应蛋白的表达和分泌最为有效。基于MME对碳源、氮源和pH值进行优化后，我们建立了XCM1培养基，其对于Xcc T3效应蛋白分泌的能力比MME强约3倍。我们进一步优化了XCM1中磷酸盐、钙和镁的浓度，发现镁浓度较低的XCM1（重新命名为XCM2）的效率约为XCM1的10倍（同时，比MME强约30倍）。因此，我们建立了一种诱导培养基XCM2，它更适合于Xcc中T3效应蛋白的分泌。
