Abstract：
The genus Hanseniaspora is characterized by some of the smallest genomes among budding yeasts. These fungi are primarily found on plant surfaces and in fermented products and represent promising biocontrol agents against notorious fungal plant pathogens. In this work, we identify pantothenate auxotrophy of a Hanseniaspora meyeri isolate that shows strong antagonism against the plant pathogen Fusarium oxysporum. Furthermore, strong biocontrol activity in vitro required both pantothenate and biotin in the growth medium. We show that the H. meyeri isolate APC 12.1 can obtain the vitamin from plants and other fungi. The underlying reason for the auxotrophy is the lack of two key pantothenate biosynthesis genes, but six genes encoding putative pantothenate transporters are present in the genome. By constructing and using a Saccharomyces cerevisiae reporter strain, we identified one Hanseniaspora transporter that conferred pantothenate uptake activity to S. cerevisiae. Pantothenate auxotrophy is rare and has been described in only a few bacteria and in S. cerevisiae strains that were isolated from sake. Such auxotrophic strains may seem an unexpected and unlikely choice as potential biocontrol agents, but they may be particularly competitive in their ecological niche and their specific growth requirements are an inherent biocontainment strategy preventing uncontrolled growth in the environment. Auxotrophic strains, such as the H. meyeri isolate APC 12.1, may thus represent a promising strategy for developing biocontrol agents that will be easier to register than prototrophic strains, which are normally used for such applications. IMPORTANCE As a precursor of the essential coenzyme A (CoA), pantothenate is present in all organisms. Plants, bacteria, and fungi are known to synthesize this vitamin, while animals must obtain it through their diet. Pantothenate auxotrophy has not been described in naturally occurring, environmental fungi and is an unexpected property for an antagonistic yeast. Here, we report that yeasts from the genus Hanseniaspora lack key enzymes for pantothenate biosynthesis and identify a transporter responsible for the acquisition of pantothenate from the environment. Hanseniaspora isolates are strong antagonists of fungal plant pathogens. Their pantothenate auxotrophy is a natural biocontainment feature that could make such isolates interesting candidates for new biocontrol approaches and allow easier registration as plant protection agents than prototrophic strains.
摘要：
Hanseniaspora属的特征是出芽酵母中一些最小的基因组。这些真菌主要存在于植物表面和发酵产品中，代表了针对臭名昭著的真菌植物病原体的有希望的生物防治剂。在这项工作中,我们确定了Hanseniasporameyeri分离物的泛酸营养缺陷型，该分离物显示出对植物病原体尖孢镰刀菌的强烈拮抗作用。此外，强的体外生物防治活性需要泛酸和生物素在生长培养基中。我们证明H.meyeri分离株APC12.1可以从植物和其他真菌中获得维生素。营养缺陷型的根本原因是缺乏两个关键的泛酸生物合成基因，但是基因组中存在六个编码推定的泛酸转运蛋白的基因。通过构建和使用酿酒酵母报告菌株，我们确定了一种Hanseniaspora转运蛋白，可将泛酸吸收活性赋予酿酒酵母。泛酸营养缺陷型很少见，仅在少数细菌和从清酒中分离出的酿酒酵母菌株中进行了描述。这种营养缺陷型菌株似乎是一个意想不到的和不太可能的选择作为潜在的生物防治剂。但是它们在生态位可能特别有竞争力，它们的特定生长要求是一种固有的生物遏制策略，可以防止环境中不受控制的生长。营养过剩菌株，例如H.meyeri分离株APC12.1，因此可能代表了开发生物控制剂的有希望的策略，该生物控制剂比原养型菌株更容易注册，通常用于此类应用。重要性作为必需辅酶A（CoA）的前体，泛酸存在于所有生物体中。植物,细菌,已知真菌合成这种维生素，而动物必须通过饮食获得它。泛酸营养缺陷型还没有在自然发生的描述，环境真菌，是拮抗酵母的一个意想不到的特性。这里,我们报告说，来自Hanseniaspora属的酵母缺乏泛酸生物合成的关键酶，并鉴定了负责从环境中获得泛酸的转运蛋白。Hanseniaspora分离株是真菌植物病原体的强拮抗剂。它们的泛酸营养缺陷型是一种天然的生物围护特征，可以使此类分离株成为新生物防治方法的有趣候选者，并且比原养型菌株更容易注册为植物保护剂。
