Table_1_The Human Microbiome as a Focus of Antibiotic Discovery: Neisseria mucosa Displays Activity Against Neisseria gonorrhoeae.XLSX

Neisseria gonorrhoeae infections are a serious global health problem. This organism has developed disturbing levels of antibiotic resistance, resulting in the need for new approaches to prevent and treat gonorrhea. The genus Neisseria also includes several members of the human microbiome that live in close association with an array of microbial partners in a variety of niches. We designed an undergraduate antibiotic discovery project to examine a panel of nonpathogenic Neisseria species for their ability to produce antimicrobial secondary metabolites. Five strains belonging to the N. mucosa species group displayed activity against other Neisseria in delayed antagonism assays; three of these were active against N. gonorrhoeae. The antimicrobial compound secreted by N. mucosa NRL 9300 remained active in the presence of catalase, trypsin, and HEPES buffer, and effectively inhibited a DNA uptake mutant of N. gonorrhoeae. Antimicrobial activity was also retained in an ethyl acetate extract of plate grown N. mucosa NRL 9300. These data suggest N. mucosa produces an antimicrobial secondary metabolite that is distinct from previously described antigonococcal agents. This work also serves as a demonstration project that could easily be adapted to studying other members of the human microbiome in undergraduate settings. We offer the perspective that both introductory and more advanced course-based and apprentice-style antibiotic discovery projects focused on the microbiome have the potential to enrich undergraduate curricula and we describe transferrable techniques and strategies to facilitate project design.

淋病奈瑟菌（Neisseria gonorrhoeae）感染是一类严重的全球性公共卫生问题。该病原菌已出现令人担忧的抗生素耐药水平，使得亟需开发全新的淋病预防与治疗手段。奈瑟菌属（Neisseria）还包含数种人体微生物组（human microbiome）成员，它们与一系列微生物伙伴紧密共生，栖息于多种生态位中。我们设计了一项本科生抗生素发现项目，旨在筛选一组非致病性奈瑟菌属物种，检测其产生抗菌次级代谢产物（secondary metabolites）的能力。属于黏膜奈瑟菌（N. mucosa）物种群的5株菌株在延迟拮抗实验（delayed antagonism assays）中，展现出对其他奈瑟菌的抑制活性；其中3株对淋病奈瑟菌具有抑制效果。黏膜奈瑟菌NRL 9300分泌的抗菌化合物在过氧化氢酶（catalase）、胰蛋白酶（trypsin）和HEPES缓冲液（HEPES buffer）存在的情况下仍保持活性，且可有效抑制淋病奈瑟菌的DNA摄取突变株（DNA uptake mutant）。平板培养的黏膜奈瑟菌NRL 9300的乙酸乙酯（ethyl acetate）提取物中，同样保留了抗菌活性。上述实验数据表明，黏膜奈瑟菌可产生一种与此前已报道的抗淋球菌制剂（antigonococcal agents）截然不同的抗菌次级代谢产物。本研究同时也是一项示范性项目，可轻松适配本科生科研场景下的人体微生物组其他成员研究。我们认为，无论是面向入门级还是进阶级的、基于课程的（course-based）或以学徒制模式（apprentice-style）开展的微生物组相关抗生素发现项目，均具备丰富本科生课程体系（undergraduate curricula）的潜力；同时本文还介绍了可复用的实验技术与项目设计策略，以助力相关研究的开展。