Frisvad Jens C
Section of Eukaryotic Biotechnology, Department of Systems Biology, Technical University of Denmark Kongens Lyngby, Denmark.
Front Microbiol. 2015 Jan 12;5:773. doi: 10.3389/fmicb.2014.00773. eCollection 2014.
Aspergillus, Penicillium, and Talaromyces are among the most chemically inventive of all fungi, producing a wide array of secondary metabolites (exometabolites). The three genera are holophyletic in a cladistic sense and polythetic classes in an anagenetic or functional sense, and contain 344, 354, and 88 species, respectively. New developments in classification, cladification, and nomenclature have meant that the species, series, and sections suggested are natural groups that share many extrolites, including exometabolites, exoproteins, exocarbohydrates, and exolipids in addition to morphological features. The number of exometabolites reported from these species is very large, and genome sequencing projects have shown that a large number of additional exometabolites may be expressed, given the right conditions ("cryptic" gene clusters for exometabolites). The exometabolites are biosynthesized via shikimic acid, tricarboxylic acid cycle members, nucleotides, carbohydrates or as polyketides, non-ribosomal peptides, terpenes, or mixtures of those. The gene clusters coding for these compounds contain genes for the biosynthetic building blocks, the linking of these building blocks, tailoring enzymes, resistance for own products, and exporters. Species within a series or section in Aspergillus, Penicillium, and Talaromyces have many exometabolites in common, seemingly acquired by cladogenesis, but some the gene clusters for autapomorphic exometabolites may have been acquired by horizontal gene transfer. Despite genome sequencing efforts, and the many breakthroughs these will give, it is obvious that epigenetic factors play a large role in evolution and function of chemodiversity, and better methods for characterizing the epigenome are needed. Most of the individual species of the three genera produce a consistent and characteristic profile of exometabolites, but growth medium variations, stimulation by exometabolites from other species, and variations in abiotic intrinsic and extrinsic environmental factors such as pH, temperature, redox potential, and water activity will add significantly to the number of biosynthetic families expressed in anyone species. An example of the shared exometabolites in a natural group such as Aspergillus section Circumdati series Circumdati is that most, but not all species produce penicillic acids, aspyrones, neoaspergillic acids, xanthomegnins, melleins, aspergamides, circumdatins, and ochratoxins, in different combinations.
曲霉属、青霉属和篮状菌属是所有真菌中最具化学创造力的，能产生各种各样的次生代谢产物（胞外代谢产物）。从系统发育的角度来看，这三个属是单系的，从进化或功能的角度来看是多型类群，分别包含344、354和88个物种。分类、系统分支和命名法的新进展意味着所建议的物种、系列和组是自然群体，除形态特征外，它们还共享许多胞外产物，包括胞外代谢产物、胞外蛋白质、胞外碳水化合物和胞外脂质。从这些物种中报道的胞外代谢产物数量非常多，基因组测序项目表明，在合适的条件下（胞外代谢产物的“隐秘”基因簇），可能会表达大量额外的胞外代谢产物。胞外代谢产物通过莽草酸途径、三羧酸循环成员、核苷酸、碳水化合物生物合成，或者作为聚酮化合物、非核糖体肽、萜类化合物或它们的混合物生物合成。编码这些化合物的基因簇包含生物合成构件的基因、这些构件的连接、修饰酶、对自身产物的抗性以及输出蛋白。曲霉属、青霉属和篮状菌属中一个系列或组内的物种有许多共同的胞外代谢产物，似乎是通过分支进化获得的，但一些独特胞外代谢产物的基因簇可能是通过水平基因转移获得的。尽管进行了基因组测序工作，并且这些工作将带来许多突破，但很明显表观遗传因素在化学多样性的进化和功能中起着很大作用，因此需要更好的方法来表征表观基因组。这三个属的大多数单个物种都会产生一致且具有特征性的胞外代谢产物谱，但生长培养基的变化、来自其他物种的胞外代谢产物的刺激，以及非生物内在和外在环境因素（如pH值,温度,氧化还原电位和水分活度）的变化，将显著增加任何一个物种中表达的生物合成家族的数量。在一个自然群体（如曲霉属烟曲霉组烟曲霉系列）中共享的胞外代谢产物的一个例子是，大多数但不是所有物种会以不同组合产生青霉酸、曲霉吡喃酮、新曲霉酸、黄天精、蜜曲霉酸、曲霉酰胺、烟曲菌素和赭曲霉毒素。
