Planta Piloto de Procesos Industriales Microbiológicos (PROIMI-CONICET), Tucumán, Argentina.
Institut für Molekulare Mikrobiologie und Biotechnologie (IMMB), Westfälische Wilhelms Universität Münster, Münster, Germany.
PLoS One. 2020 Sep 18;15(9):e0239432. doi: 10.1371/journal.pone.0239432. eCollection 2020.
Only quite recently, we have shown that yeast strains Clavispora lusitaniae 146 and Pichia fermentans 27 can act as efficient biocontrol agents for combating postharvest fungal diseases in lemons. During postharvest and storage conditions, microorganisms are subject to different stress factors that could affect both their survival and their protective capacity. Understanding the tolerance of yeasts to environmental stress factors could support the future development and commercial application of biological control formulations based on such organisms. Thus, the impact of different stressors on the viability and protection efficiency of C. lusitaniae strain 146 and P. fermentans strain 27 was evaluated, and the yeasts were subjected to oxidative stress, thermal treatments, exposure to NaOCl, osmotic stress, and ultraviolet irradiation. Candida oleophila strain O served as the reference control. C. lusitaniae 146 was more resistant to H2O2 in plate assays; however, in liquid media there was no significant difference to the other strains. Strain 146 was less affected by NaOCl, being able to survive with 300 ppm. P. fermentans 27 was the strain most heavily affected by osmotic pressure, while strains 146 and strain O showed a similar adaptation. UV-B irradiation severely affected C. oleophila and P. fermentans, while C. lusitaniae was the most resistant. Strains 146 and 27 were similarly tolerant to thermal shocks, compared to the reference strain, which was less viable. In in vivo tests, exposure to 10 mM H2O2, 45°C or 200 ppm NaOCl prior to fruit inoculation, reduced the antagonistic activity against the pathogen Penicillium digitatum. However, in no case was the biocontrol efficiency reduced to less than 50%. As C. lusitaniae 146 demonstrated a great potential to combat P. digitatum under a wide range of conditions, the organism is a promising candidate as an effective and valuable alternative to toxic fungicides.
直到最近，我们才发现，克鲁维毕赤酵母（Clavispora lusitaniae）146 菌株和发酵毕赤酵母（Pichia fermentans）27 菌株可以作为防治柠檬采后真菌病害的有效生防制剂。在采后和贮藏过程中，微生物会受到不同的胁迫因子的影响，这些因子会影响它们的生存能力和保护能力。了解酵母对环境胁迫因子的耐受性可以为基于这些生物的生物防治制剂的未来开发和商业应用提供支持。因此，评估了不同胁迫因子对克鲁维毕赤酵母（Clavispora lusitaniae）146 菌株和发酵毕赤酵母（Pichia fermentans）27 菌株的生存能力和保护效率的影响，并对酵母进行了氧化应激、热处理、次氯酸钠暴露、渗透压和紫外线照射处理。威克汉姆毕赤酵母（Candida oleophila）O 菌株作为对照。在平板试验中，146 菌株对 H2O2 的抗性更强；然而，在液体培养基中，与其他菌株没有显著差异。146 菌株对次氯酸钠的影响较小，能够在 300 ppm 的浓度下存活。发酵毕赤酵母（Pichia fermentans）27 菌株对渗透压的影响最大，而 146 菌株和 O 菌株的适应能力相似。UV-B 辐射严重影响威克汉姆毕赤酵母（Candida oleophila）和发酵毕赤酵母（Pichia fermentans），而克鲁维毕赤酵母（Clavispora lusitaniae）的抗性最强。与对照菌株相比，146 菌株和 27 菌株对热冲击的耐受性相似，对照菌株的生存能力较低。在体内试验中，在果实接种前用 10 mM H2O2、45°C 或 200 ppm 次氯酸钠处理，会降低对病原菌柑橘绿霉（Penicillium digitatum）的拮抗活性。然而，在任何情况下，生防效率都没有降低到 50%以下。由于克鲁维毕赤酵母（Clavispora lusitaniae）146 菌株在广泛的条件下表现出对柑橘绿霉（Penicillium digitatum）的巨大防治潜力，因此该菌是一种很有前途的候选生物防治制剂，可作为毒性杀菌剂的有效且有价值的替代品。
