Fuentes Flores Andrés, Sepúlveda Cisternas Ignacio, Vásquez Solis de Ovando José Ignacio, Torres Alexia, García-Angulo Víctor Antonio
Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.
Escuela de Biotecnología, Universidad Mayor, Campus Huechuraba, Santiago, Chile.
Gut Pathog. 2017 Nov 14;9:64. doi: 10.1186/s13099-017-0214-9. eCollection 2017.
The waterborne diarrheagenic bacterium , cause of the pandemic cholera disease, thrives in a variety of environments ranging from estuarine waters to the human intestinal tract. This species has two ways to obtain the essential micronutrient riboflavin, de novo biosynthesis and environmental uptake through the RibN importer. The way these functions interrelate to fulfill riboflavin needs in different conditions in this species is unknown.
This study analyzed the contributions of riboflavin biosynthesis and transport to the culturability of in river and seawater in vitro and in the nematode host model. Elimination of the riboflavin biosynthetic gene renders the bacteria riboflavin-auxotrophic, while a mutant strain has no growth defect in minimal media. When growing in river water, deletion of causes an impairment in culturability. In this condition, the ∆ strain has a defect to compete against a wild type strain but outcompetes the ∆ strain. The latter effect is inverted by the addition of riboflavin to the water. In contrast, growth in seawater causes a loss in culturability independent of riboflavin biosynthesis or transport. In the model, only the ∆ strain is attenuated.
Results indicate that while riboflavin biosynthesis seems to outweigh riboflavin uptake, the latter may still provide a selective advantage to in some environments.
霍乱弧菌是一种通过水传播的致泻性细菌，是霍乱大流行疾病的病原体，在从河口到人类肠道的各种环境中都能茁壮成长。该物种有两种获取必需微量营养素核黄素的途径，即从头生物合成和通过RibN转运蛋白从环境中摄取。在该物种的不同条件下，这些功能如何相互关联以满足核黄素需求尚不清楚。
本研究分析了核黄素生物合成和转运对霍乱弧菌在河流和海水中的体外培养能力以及对线虫宿主模型的影响。消除霍乱弧菌的核黄素生物合成基因会使细菌成为核黄素营养缺陷型，而ribN突变菌株在基本培养基中没有生长缺陷。在河水中生长时，删除ribN会导致培养能力受损。在这种情况下，ΔribN菌株与野生型菌株竞争存在缺陷，但比Δriboflavin菌株更具竞争力。添加核黄素到水中会使后一种效果反转。相比之下，在海水中生长会导致培养能力丧失，与核黄素生物合成或转运无关。在秀丽隐杆线虫模型中，只有Δriboflavin菌株减弱。
结果表明，虽然核黄素生物合成似乎比核黄素摄取更为重要，但后者在某些环境中仍可能为霍乱弧菌提供选择优势。
