PDF(Pubmed)
Abstract：
BACKGROUND: Ascomycetous budding yeasts are ubiquitous environmental microorganisms important in food production and medicine. Due to recent intensive genomic research, the taxonomy of yeast is becoming more organized based on the identification of monophyletic taxa. This includes genera important to humans, such as Kazachstania. Until now, Kazachstania humilis (previously Candida humilis) was regarded as a sourdough-specific yeast. In addition, any antibacterial activity has not been associated with this species.
RESULTS: Previously, we isolated a yeast strain that impaired bio-hydrogen production in a dark fermentation bioreactor and inhibited the growth of Gram-positive and Gram-negative bacteria. Here, using next generation sequencing technologies, we sequenced the genome of this strain named K. humilis MAW1. This is the first genome of a K. humilis isolate not originating from a fermented food. We used novel phylogenetic approach employing the 18 S-ITS-D1-D2 region to show the placement of the K. humilis MAW1 among other members of the Kazachstania genus. This strain was examined by global phenotypic profiling, including carbon sources utilized and the influence of stress conditions on growth. Using the well-recognized bacterial model Escherichia coli AB1157, we show that K. humilis MAW1 cultivated in an acidic medium inhibits bacterial growth by the disturbance of cell division, manifested by filament formation. To gain a greater understanding of the inhibitory effect of K. humilis MAW1, we selected 23 yeast proteins with recognized toxic activity against bacteria and used them for Blast searches of the K. humilis MAW1 genome assembly. The resulting panel of genes present in the K. humilis MAW1 genome included those encoding the 1,3-β-glucan glycosidase and the 1,3-β-glucan synthesis inhibitor that might disturb the bacterial cell envelope structures.
CONCLUSIONS: We characterized a non-sourdough-derived strain of K. humilis, including its genome sequence and physiological aspects. The MAW1, together with other K. humilis strains, shows the new organization of the mating-type locus. The revealed here pH-dependent ability to inhibit bacterial growth has not been previously recognized in this species. Our study contributes to the building of genome sequence-based classification systems; better understanding of K.humilis as a cell factory in fermentation processes and exploring bacteria-yeast interactions in microbial communities.
RESULTS: Previously, we isolated a yeast strain that impaired bio-hydrogen production in a dark fermentation bioreactor and inhibited the growth of Gram-positive and Gram-negative bacteria. Here, using next generation sequencing technologies, we sequenced the genome of this strain named K. humilis MAW1. This is the first genome of a K. humilis isolate not originating from a fermented food. We used novel phylogenetic approach employing the 18 S-ITS-D1-D2 region to show the placement of the K. humilis MAW1 among other members of the Kazachstania genus. This strain was examined by global phenotypic profiling, including carbon sources utilized and the influence of stress conditions on growth. Using the well-recognized bacterial model Escherichia coli AB1157, we show that K. humilis MAW1 cultivated in an acidic medium inhibits bacterial growth by the disturbance of cell division, manifested by filament formation. To gain a greater understanding of the inhibitory effect of K. humilis MAW1, we selected 23 yeast proteins with recognized toxic activity against bacteria and used them for Blast searches of the K. humilis MAW1 genome assembly. The resulting panel of genes present in the K. humilis MAW1 genome included those encoding the 1,3-β-glucan glycosidase and the 1,3-β-glucan synthesis inhibitor that might disturb the bacterial cell envelope structures.
CONCLUSIONS: We characterized a non-sourdough-derived strain of K. humilis, including its genome sequence and physiological aspects. The MAW1, together with other K. humilis strains, shows the new organization of the mating-type locus. The revealed here pH-dependent ability to inhibit bacterial growth has not been previously recognized in this species. Our study contributes to the building of genome sequence-based classification systems; better understanding of K.humilis as a cell factory in fermentation processes and exploring bacteria-yeast interactions in microbial communities.
摘要：
背景：子囊出芽酵母是普遍存在的环境微生物，在食品生产和医药中很重要。由于最近密集的基因组研究，基于单系分类群的鉴定，酵母的分类学变得更加有条理。这包括对人类重要的属，比如Kazachstania.直到现在,Hazachstaniahumilis（以前是Humilis念珠菌）被认为是酸面团特异性酵母。此外,任何抗菌活性与该物种无关。
结果：以前，我们分离了一个酵母菌株，该菌株在黑暗发酵生物反应器中损害了生物氢的产生，并抑制了革兰氏阳性和革兰氏阴性细菌的生长。这里,使用下一代测序技术，我们对这个名为K.humilisMAW1的菌株的基因组进行了测序。这是不源自发酵食品的胡叶木分离物的第一个基因组。我们使用了新的系统发育方法，采用了18S-ITS-D1-D2区域，以显示哈木树MAW1在Kazachstania属其他成员中的位置。通过全球表型分析检查了该菌株，包括利用的碳源和胁迫条件对生长的影响。使用公认的细菌模型大肠杆菌AB1157，我们表明在酸性培养基中培养的K.humilisMAW1通过细胞分裂的干扰抑制细菌生长，表现为细丝的形成。为了更深入地了解胡志明市MAW1的抑制作用，我们选择了23种具有公认的细菌毒性活性的酵母蛋白，并将其用于胡志明市MAW1基因组组装的Blast搜索。所得到的存在于胡枝子MAW1基因组中的一组基因包括编码可能干扰细菌细胞包膜结构的1,3-β-葡聚糖糖苷酶和1,3-β-葡聚糖合成抑制剂的基因。
结论：我们表征了一种非酸面团衍生的树枝菌菌株，包括其基因组序列和生理方面。MAW1，以及其他humilis菌株，显示了交配型基因座的新组织。此处揭示的pH依赖性抑制细菌生长的能力先前尚未在该物种中得到认可。我们的研究有助于建立基于基因组序列的分类系统;更好地理解K.humilis作为发酵过程中的细胞工厂，并探索微生物群落中的细菌-酵母相互作用。
结果：以前，我们分离了一个酵母菌株，该菌株在黑暗发酵生物反应器中损害了生物氢的产生，并抑制了革兰氏阳性和革兰氏阴性细菌的生长。这里,使用下一代测序技术，我们对这个名为K.humilisMAW1的菌株的基因组进行了测序。这是不源自发酵食品的胡叶木分离物的第一个基因组。我们使用了新的系统发育方法，采用了18S-ITS-D1-D2区域，以显示哈木树MAW1在Kazachstania属其他成员中的位置。通过全球表型分析检查了该菌株，包括利用的碳源和胁迫条件对生长的影响。使用公认的细菌模型大肠杆菌AB1157，我们表明在酸性培养基中培养的K.humilisMAW1通过细胞分裂的干扰抑制细菌生长，表现为细丝的形成。为了更深入地了解胡志明市MAW1的抑制作用，我们选择了23种具有公认的细菌毒性活性的酵母蛋白，并将其用于胡志明市MAW1基因组组装的Blast搜索。所得到的存在于胡枝子MAW1基因组中的一组基因包括编码可能干扰细菌细胞包膜结构的1,3-β-葡聚糖糖苷酶和1,3-β-葡聚糖合成抑制剂的基因。
结论：我们表征了一种非酸面团衍生的树枝菌菌株，包括其基因组序列和生理方面。MAW1，以及其他humilis菌株，显示了交配型基因座的新组织。此处揭示的pH依赖性抑制细菌生长的能力先前尚未在该物种中得到认可。我们的研究有助于建立基于基因组序列的分类系统;更好地理解K.humilis作为发酵过程中的细胞工厂，并探索微生物群落中的细菌-酵母相互作用。
