Sipiczki Matthias
Department of Genetics and Applied Microbiology, University of Debrecen, 4032 Debrecen, Hungary.
Microorganisms. 2020 Jul 12;8(7):1029. doi: 10.3390/microorganisms8071029.
Yeasts affiliated with the clade (subclade) of the large ascomycetous genus frequently turn out to produce the characteristic maroon-red pulcherrimin when tested for pigment production and prove to exert antagonistic effects on many types of microorganisms. The determination of the exact taxonomic position of the strains is hampered by the shortage of distinctive morphological and physiological properties of the species of the clade and the lack of rDNA barcode gaps. The rDNA repeats of the type strains of the species are not homogenized and are assumed to evolve by a birth-and-death mechanism combined with reticulation. The taxonomic division is further hampered by the incomplete biological (reproductive) isolation of the species: certain type strains can be hybridized and genome sequencing revealed chimeric genome structures in certain strains that might have evolved from interspecies hybrids (alloploid genome duplication). Various mechanisms have been proposed for the antimicrobial antagonism. One is related to pulcherrimin production. The diffusible precursor of pulcherrimin, the pulcherriminic acid is secreted by the cells into the environment where it forms the insoluble pulcherrimin with the ferric ions. The lack of free iron caused by the immobilization of ferric ions inhibits the growth of many microorganisms. Recent results of research into the complexity of the taxonomic division of the pulcherrimin-producing yeasts and the mechanism(s) underlying their antimicrobial antagonism are discussed in this review.
隶属于大型子囊菌属进化枝（亚进化枝）的酵母，在进行色素生成测试时，常常会产生特征性的栗红色铁锈菌素，并且对多种微生物具有拮抗作用。该进化枝物种缺乏独特的形态和生理特性，以及缺少核糖体DNA条形码间隙，这使得菌株确切分类地位的确定受到阻碍。该物种模式菌株的核糖体DNA重复序列未同质化，被认为是通过生死机制与网状化相结合的方式进化而来。物种的不完全生物（生殖）隔离进一步阻碍了分类划分：某些模式菌株可以杂交，基因组测序揭示某些菌株中存在嵌合基因组结构，这些菌株可能是由种间杂种（异源多倍体基因组加倍）进化而来。针对抗菌拮抗作用提出了多种机制。一种与铁锈菌素的产生有关。铁锈菌素的可扩散前体，即铁锈酸，由细胞分泌到环境中，在那里它与铁离子形成不溶性的铁锈菌素。铁离子固定导致的游离铁缺乏抑制了许多微生物的生长。本文综述了近期关于产生铁锈菌素酵母分类划分的复杂性及其抗菌拮抗作用潜在机制的研究结果。
