Lichens, which are defined by a core symbiosis between a mycobiont (fungal partner) and a photobiont (photoautotrophic partner), are in fact complex assemblages of microorganisms that constitute a largely untapped source of bioactive secondary metabolites. Historically, compounds isolated from lichens have predominantly been those produced by the dominant fungal partner, and these continue to be of great interest for their unique chemistry and biotechnological potential. In recent years it has become apparent that many photobionts and lichen-associated bacteria also produce a range of potentially valuable molecules. There is evidence to suggest that the unique nature of the symbiosis has played a substantial role in shaping many aspects of lichen chemistry, for example driving bacteria to produce metabolites that do not bring them direct benefit but are useful to the lichen as a whole. This is most evident in studies of cyanobacterial photobionts, which produce compounds that differ from free living cyanobacteria and are unique to symbiotic organisms. The roles that these and other lichen-derived molecules may play in communication and maintaining the symbiosis are poorly understood at present. Nonetheless, advances in genomics, mass spectrometry and other analytical technologies are continuing to illuminate the wealth of biological and chemical diversity present within the lichen holobiome. Implementation of novel biodiscovery strategies such as metagenomic screening, coupled with synthetic biology approaches to reconstitute, re-engineer and heterologously express lichen-derived biosynthetic gene clusters in a cultivable host, offer a promising means for tapping into this hitherto inaccessible wealth of natural products.

中文翻译：

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地衣共生的二次代谢

地衣是由真菌生物体（真菌伴侣）和光生物体（光合自养伴侣）之间的核心共生所定义的，实际上是微生物的复杂组合，它们构成了生物活性次生代谢物的主要未开发来源。从历史上看，从地衣中分离出的化合物主要是占优势的真菌伴侣产生的化合物，这些化合物因其独特的化学和生物技术潜力而继续受到人们的关注。近年来，很明显，许多光生生物和与地衣有关的细菌也产生一系列潜在有价值的分子。有证据表明，共生的独特性质在塑造地衣化学的许多方面都发挥了重要作用，例如驱使细菌产生代谢产物，这些代谢产物不会直接带来益处，但对整个地衣有用。这在对蓝细菌光生生物的研究中最为明显，该生物产生的化合物与游离的活蓝细菌不同，并且是共生生物所独有的。目前，这些和其他地衣来源的分子在交流和维持共生中可能扮演的角色还知之甚少。尽管如此，基因组学，质谱法和其他分析技术的进步仍在继续阐明地衣全生命周期中存在的丰富的生物和化学多样性。实施新颖的生物发现策略（例如宏基因组学筛选）以及合成生物学方法来重构，