Penicillium chrysogenum is a ubiquitous airborne fungus detected in every sampled region of the Earth. Owing to its role in Alexander Fleming's serendipitous discovery of Penicillin in 1928, the fungus has generated widespread scientific interest; however its natural history is not well understood. Research has demonstrated speciation within P. chrysogenum, describing the existence of four cryptic species. To discriminate the four species, we developed protocols for species-specific diagnostic PCR directly from fungal conidia. 430 Penicillium isolates were collected to apply our rapid diagnostic tool and explore the distribution of these fungi across the London Underground rail transport system revealing significant differences between Underground lines. Phylogenetic analysis of multiple type isolates confirms that the ‘Fleming species’ should be named Penicillium rubens and that divergence of the four ‘Chrysogenum complex’ fungi occurred about 0.75 million yr ago. Finally, the formal naming of two new species, Penicillium floreyi and Penicillium chainii, is performed.

产黄青霉是一种普遍存在的空气传播真菌，在地球的每个采样区域都可以检测到。由于它在 1928 年亚历山大·弗莱明 (Alexander Fleming) 偶然发现青霉素的过程中所发挥的作用，这种真菌引起了广泛的科学兴趣。然而它的自然历史还没有被很好地了解。研究已经证明了P内的物种形成。chrysogenum，描述了四种神秘物种的存在。为了区分这四个物种，我们开发了直接从真菌分生孢子进行物种特异性诊断 PCR 的方案。430青霉菌收集分离株以应用我们的快速诊断工具，并探索这些真菌在伦敦地铁运输系统中的分布，揭示地铁线路之间的显着差异。对多种分离株的系统发育分析证实，“弗莱明种”应命名为红青霉，并且四种“Chrysogenum 复合体”真菌的分化发生在大约 75 万年前。最后对两个新种Penicillium floreyi和Penicillium chainii进行了正式命名。