M.V. Lomonosov Moscow State University, Moscow, 119234, Russia; I.I. Mechnikov Research Institute of Vaccines and Sera, Moscow, 105064, Russia.
M.V. Lomonosov Moscow State University, Moscow, 119234, Russia; G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of RAS, Pushchino, 142290, Russia.
Fungal Biol. 2023 Jun;127(6):1075-1083. doi: 10.1016/j.funbio.2023.06.001. Epub 2023 Jun 2.
Yeast complexes in the composting process of cow dung prepared to fertilize the soil for growing vegetables and fruits were studied. The average abundance of yeasts changed during the four temperature stages of the composting process. The highest abundance of yeasts, 1.38 × 10 cfu/g, was observed in the second stage of heating from 20 to 40 °C; the lowest was studied in the stage with the highest temperature (65 °C), 1.68 × 10 cfu/g. A total of 19 yeast species were observed and identified: 11 ascomycetes and 8 basidiomycetes, belonging to five subphyla of Fungi: Saccharomycotina (10), Pezizomycotina (1), Agaricomycotina (5), Pucciniomycotina (2), and Ustilaginomycotina (1). The greatest diversity of yeasts was found in the initial (20 °C) and second (heating up to 40 °C) temperature stages of composting (Aureobasidium pullulans (yeast-like fungus), Candida parapsilosis, Candida saitoana, Candida santamariae, Candida tropicalis, Curvibasidium cygneicollum, Cutaneotrichosporon moniliforme, Debaryomyces fabryi, Debaryomyces hansenii, Filobasidium magnum, Kazachstania sp., Moesziomyces bullatus, Naganishia globosa, Papiliotrema flavescens, Rhodotorula mucilaginosa, Scheffersomyces insectosa, Torulaspora delbrueckii, Vanrija musci), and the lowest in the stage of maximum heating (65 °C) (C. parapsilosis, C. tropicalis, Cyberlindnera jadinii).The opportunistic yeasts C. parapsilosis and C. tropicalis were obtained not only in the initial, second and third temperature stages of the composting process, but also in mature compost in the final stage prepared for soil application. This study shows that the cow dung, used in the farm studied did not meet the microbiological safety criteria. The reduction of opportunistic yeast species was not achieved with the composting method used. The likelihood of these species entering agricultural products via compost and soil and developing as endophytes in the internal tissues of fruits is very high. Since some strains of opportunistic Candida species from cow dung exhibited virulent characteristics (they produced hydrolytic enzymes and were resistant to antifungal compounds), additional phenotypic and genetic studies of the compost strains and their comparison with clinical isolates should be pursued.
研究了牛粪堆肥过程中的酵母复合物，这些复合物旨在为种植蔬菜和水果的土壤提供养分。在堆肥过程的四个温度阶段中，酵母的平均丰度发生了变化。在从 20°C 加热到 40°C 的第二阶段，观察到最高的酵母丰度，为 1.38×10^cfu/g；在温度最高（65°C）的阶段研究到的最低丰度为 1.68×10^cfu/g。共观察到并鉴定了 19 种酵母，其中 11 种属于子囊菌门，8 种属于担子菌门，属于真菌的五个亚门：Saccharomycotina（10）、Pezizomycotina（1）、Agaricomycotina（5）、Pucciniomycotina（2）和 Ustilaginomycotina（1）。在堆肥的初始（20°C）和第二（加热至 40°C）温度阶段发现了最多的酵母多样性（类似于酵母的出芽短梗霉、近平滑假丝酵母、拟热带假丝酵母、圣塔马里亚假丝酵母、热带假丝酵母、弯颈霉、毛状外瓶霉、法夫酵母、汉逊德巴利酵母、巨形毕赤酵母、Kazachstania 属、球形瘤胃球菌、黄孢原毛平革菌、淡色被孢霉、粘红酵母、昆虫球腔菌、德尔布有孢圆酵母、卡瓦伯氏酵母），在最高加热温度（65°C）阶段发现的最少（近平滑假丝酵母、热带假丝酵母、Cyberlindnera jadinii）。机会性酵母 C. parapsilosis 和 C. tropicalis 不仅在堆肥过程的初始、第二和第三温度阶段获得，而且在为土壤应用准备的最后成熟堆肥中也获得。这项研究表明，在所研究的农场中使用的牛粪不符合微生物安全标准。使用的堆肥方法并未实现减少机会性酵母种类。这些物种通过堆肥和土壤进入农产品并在水果内部组织中作为内生菌发育的可能性非常高。由于一些来自牛粪的机会性假丝酵母菌株表现出毒力特征（它们产生水解酶并对抗真菌化合物具有抗性），因此应该进一步进行堆肥菌株的表型和遗传研究，并将其与临床分离株进行比较。
