Department of Biology, McMaster University, Hamilton, ON, Canada.
FEMS Microbiol Ecol. 2019 Sep 1;95(9). doi: 10.1093/femsec/fiz122.
Cryptococcus deneoformans is an opportunist yeast pathogen and causative agent of meningoencephalitis in humans. It is known to be mainly distributed in temperate climates. Most of our current understanding of this species has come from clinical isolates, leaving environmental populations largely unexplored. The Middle East remains one such underexplored area with no published study to date investigating cryptococcal diversity in soil. In this study, we identified 76 C. deneoformans isolates from a survey of 562 soil samples collected from six cities in Saudi Arabia. Multilocus sequence typing revealed the presence of two major sequence types (STs), ST160 (n = 63) and ST294 (n = 9), along with four singleton STs, three of which were novel. One novel ST, ST613, was likely a recombinant product between ST160 and ST294. Among the 76 isolates, 75 belonged to mating type (MAT)α while one isolate was MATa. Our analyses suggest that the Saudi Arabian C. deneoformans population likely reproduces both asexually and sexually in nature. Our study is the first to report the occurrence of C. deneoformans in a desert climate, representing a novel expansion to this species' currently known ecological niche.
新生隐球菌是一种机会性酵母病原体，也是人类脑膜脑炎的病原体。它主要分布在温带气候中。我们目前对该物种的大部分了解来自临床分离株，而对环境种群的了解则很少。中东就是一个未被充分探索的地区，迄今为止，没有发表过研究土壤中隐球菌多样性的研究。在这项研究中，我们从沙特阿拉伯六个城市采集的 562 个土壤样本中调查了 76 株新生隐球菌分离株。多位点序列分型显示存在两种主要的序列型（ST），ST160（n = 63）和 ST294（n = 9），以及四个单峰 ST，其中三个是新的。一个新的 ST，ST613，可能是 ST160 和 ST294 之间的重组产物。在 76 株分离株中，75 株属于交配型（MAT）α，而一株为 MATa。我们的分析表明，沙特阿拉伯的新生隐球菌种群可能在自然条件下既进行无性繁殖又进行有性繁殖。我们的研究首次报道了新生隐球菌在沙漠气候中的发生，代表了该物种目前已知生态位的一个新扩展。
