Some soil microorganisms, especially bacteria and mycorrhizal fungi, play a role in the promotion of plant growth. However, plant growth promotion involving yeasts in soil has not yet been extensively investigated. This study aimed to isolate and identify yeast strains obtained from soils of the Assam tea plant (Camellia sinensis var. assamica) in northern Thailand and to investigate their plant growth promoting capabilities. A total of 42 yeast strains were obtained and identified by analysis of the D1/D2 domain of the large subunit ribosomal RNA gene. We identified 35 strains of six species belonging to the phylum Ascomycota, namely Aureobasidium melanogenum, Kazachstania aquatica, Saturnispora diversa, Saturnispora sekii, Schwanniomyces pseudopolymorphus and Wickerhamomyces anomalus, and six species were determined to belong to the phylum Basidiomycota, namely Apiotrichum scarabaeorum, Curvibasidium pallidicorallinum, Papiliotrema laurentii, Rhodosporidiobolus ruineniae, Trichosporon asahii and Trichosporon coremiiforme. Seven strains were representative of potential new species and belonged to the genera Galactomyces and Wickerhamomyces. A total of 28 strains were found to produce indole-3-acetic acid (IAA) in a range of 2.12 to 37.32 mg/L, with the highest amount of IAA produced by R. ruineniae SDBR-CMU-S1-03. All yeast strains were positive in terms of ammonia production, and only eight strains were positive for siderophore production. Two yeast species, P. laurentii and W. anomalus, were able to solubilize the insoluble form of calcium and zinc. The ability to produce amylase, endogulcanase, lipase, pectinase, protease and xylanase was dependent upon the yeast species and strain involved.

中文翻译：

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从泰国北部的阿萨姆邦茶（Camellia sinensis var。assamica）人工林土壤中分离的酵母对多种植物生长促进试验的评价。

一些土壤微生物，特别是细菌和菌根真菌，在促进植物生长中起作用。然而，尚未广泛研究涉及土壤中的酵母的植物生长促进。本研究旨在从阿萨姆红茶厂（土壤得到分离和鉴定酵母菌株茶树变种普洱茶在泰国北部，探讨其促进植物生长的能力）。通过分析大亚基核糖体RNA基因的D1 / D2结构域，获得并鉴定了总共42个酵母菌株。我们确定了6个属的子囊门菌属的35个菌株，分别是黑色金黄担子，水生哈萨克斯坦，水生Saturnispora diversa，土生Saturnispora sekii，假单胞菌Schwanniomyces pseudopolymorphus和Wickerhamomyces anomalus以及6个属被确定为Basidiomycota菌门的种，即尖顶青霉，Curvibasidium pallidicorallinum，Papiliotrema laurentii，Rhodosporidiobolus Ruieniae，Trichosporona asahii和Trichosporon。七个菌株代表潜在的新物种，属于半乳杆菌属和柳条杆菌属。发现总共28个菌株产生的吲哚-3-乙酸（IAA）范围为2.12至37.32 mg / L，其中R产生的IAA量最高。科SDBR-CMU-S1-03。就氨产生而言，所有酵母菌株均为阳性，而仅铁载体产生为八株。两种酵母菌，劳德氏假单胞菌和异常W.酵母，能够溶解钙和锌的不溶形式。产生淀粉酶，内切葡聚糖酶，脂肪酶，果胶酶，蛋白酶和木聚糖酶的能力取决于所涉及的酵母种类和菌株。