Di Piazza Simone, Houbraken Jos, Meijer Martin, Cecchi Grazia, Kraak Bart, Rosa Ester, Zotti Mirca
Laboratory of Mycology, DISTAV Department of Earth, Environmental and Life Science, University of Genoa, Corso Europa 26, 16132 Genoa, Italy.
Applied and Industrial Mycology, Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
Microorganisms. 2020 Jun 11;8(6):880. doi: 10.3390/microorganisms8060880.
Composting is a complex process in which various micro-organisms, mainly fungi and bacteria, are involved. The process depends on a large number of factors (biological, chemical, and physical) among which microbial populations play a fundamental role. The high temperatures that occur during the composting process indicate the presence of thermotolerant and thermophilic micro-organisms that are key for the optimization of the process. However, the same micro-organisms can be harmful (allergenic, pathogenic) for workers that handle large quantities of material in the plant, and for end users, for example, in the indoor environment (e.g., pots in houses and offices). Accurate knowledge of thermotolerant and thermophilic organisms present during the composting stages is required to find key organisms to improve the process and estimate potential health risks. The objective of the present work was to study thermotolerant and thermophilic mycobiota at different time points of compost maturation. Fungi were isolated at four temperatures (25, 37, 45, and 50 °C) from compost samples collected at five different steps during a 21-day compost-maturation period in an active composting plant in Liguria (northwestern Italy). The samples were subsequently plated on three different media. Our results showed a high presence of fungi with an order of magnitude ranging from 1 × 10 to 3 × 10 colony-forming units (CFU) g. The isolated strains, identified by means of specific molecular tools (ITS, beta-tubulin, calmodulin, elongation factor 1-alpha, and LSU sequencing), belonged to 45 different species. Several thermophilic species belonging to genera and were detected, which could be key during composting. Moreover, the presence of several potentially harmful fungal species, such as , and were found during the whole process, including the final product. Results highlighted the importance of surveying the mycobiota involved in the composting process in order to: (i) find solutions to improve efficiency and (ii) reduce health risks.
堆肥是一个复杂的过程，涉及各种微生物，主要是真菌和细菌。该过程取决于大量因素（生物、化学和物理），其中微生物群落起着至关重要的作用。堆肥过程中出现的高温表明存在耐热和嗜热微生物，它们是优化该过程的关键。然而，同样的微生物可能对在工厂中处理大量物料的工人以及终端用户（例如在室内环境中，如房屋和办公室的花盆中）有害（具有致敏性、致病性）。需要准确了解堆肥阶段存在的耐热和嗜热生物，以找到改善该过程的关键生物并估计潜在的健康风险。本研究的目的是在堆肥成熟的不同时间点研究耐热和嗜热真菌群落。在利古里亚（意大利西北部）一个活跃的堆肥工厂中，在21天的堆肥成熟期间，从五个不同步骤收集的堆肥样品中，在四个温度（25、37、45和50°C）下分离真菌。随后将样品接种在三种不同的培养基上。我们的结果表明，真菌数量很高，数量级范围为1×10至3×10菌落形成单位（CFU）/克。通过特定的分子工具（ITS、β-微管蛋白、钙调蛋白、延伸因子1-α和LSU测序）鉴定的分离菌株属于45个不同的物种。检测到了几种属于特定属的嗜热物种，它们可能是堆肥过程中的关键物种。此外，在整个过程中，包括最终产品中，发现了几种潜在有害的真菌物种，如特定的属。结果强调了调查堆肥过程中涉及的真菌群落的重要性，以便：（i）找到提高效率的解决方案和（ii）降低健康风险。
