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Rice cultivation is widely used to improve saline-sodic soils in Northeast China. However, the chronological effect of rice cultivation on soil fungal communities has not been studied. Therefore, this study investigated the variation of soil fungal communities in different rice cultivation years. Compared with the blank area, the rice cultivation for 20 years significantly decreased the pH and electrical conductivity by 16.6% and 70.1%, while significantly increased the soil organic carbon and available phosphorus by 90.6% and 17.4 times, respectively. Meanwhile, the relative abundance of Ascomycota and Basidiomycota significantly decreased and increased after rice cultivation, respectively. Moreover, some genera of arbuscular mycorrhizal fungi (AMF), e.g. Corymbiglomus, Glomus, and Rhizophagus, and pathogenic fungi (Thanatephorus cucumeris) disappeared, while Dentiscutata (one genus of AMF) appeared after rice cultivation. In addition, the fungal richness significantly increased when the rice cultivation less than 15 years and the fungal communities were similar between 15 and 20 years. Our findings showed that rice cultivation improved the nutrient availability and reduced salinity-alkalinity stress of sodic soils. After the rice cultivation for 15 years, the soil fungal community tended to be stable. [ABSTRACT FROM AUTHOR]

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 × 104 to 3 × 105 colony-forming units (CFU) g−1. 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 Thermoascus and Thermomyces were detected, which could be key during composting. Moreover, the presence of several potentially harmful fungal species, such as Aspergillus fumigatus, A. terreus, and Scedosporium apiospermum, 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.

Current methods for fungi contamination determination in peanuts are usually labor-intensive and time-consuming. In this paper, a new method for rapid detection of the contamination by harmful fungi species in peanut kernels based on electronic nose (E-nose) technology was investigated. Peanut samples were firstly irradiated by Co-60 gamma radiation with a dose of 15 kGy to kill all fungi on or within kernels. After irradiation, clean and sterile peanuts were placed in moist chambers and inoculated with 5 different spore suspensions of aspergillus spp., which were A. flavus 3.17, A. flavus 3.395 0, A. parasiticus 3.395, A. parasiticus 3.012 4 and A. ochraceus 3.648 6, the former 3 of which were aflatoxin (AFT) producer, and the latter one was ochratoxin (OT) producer. Spore suspensions were prepared by blending the 7-day old colonies cultured on potato dextrose agar (PDA) with ultrapure sterilized water. Initial spore concentration was about 5 log (CFU/mL), and then 10 μL spore suspension was dropped onto individual peanut sample by a pipette. All infected samples were stored at 26 ℃ and 80% relative humidity (RH) for 9 d until all peanut samples were covered with a mass of fungi. Subsequently, the E-nose (Fox 3000, Alpha Mos) was used for the collection of volatile odor information from peanut samples stored for 0, 3, 6 and 9 d, respectively. Finally, response signals of 12 E-nose sensors were extracted by multivariate statistical analysis method. Qualitative and quantitative models for the determination of harmful fungi contamination in peanuts were established. The principal component analysis (PCA) results showed that peanut samples with different storage days could be successfully discriminated for different fungal infection levels. Loading analysis of E-nose sensors indicated that the sensors of T70/2, LY2/LG, P10/1, T30/1 were found to be more sensitive than other sensors. These sensors might play an important role in the discrimination of samples, which provided a reference for the development of special-purpose sensor systems for peanut samples in future. The changes in volatile compounds of infected peanut samples could be mainly attributed to oxynitride, hydrocarbon and aromatic compounds. For the classification of peanut samples with different infection levels, the correct rate of 100%(or approaching) was obtained by linear discriminant analysis (LDA) models. The results also verified the possibility of discriminating peanuts infection by different fungi species. In addition, good correlation between E-nose signals and colony forming units in peanut samples was obtained by partial least squares regression (PLSR) analysis models. The coefficient of determination for the prediction set (Rp2) and the root mean square error of prediction (RMSEP) for the prediction models were 0.814 5 and 0.244 0 lg (CFU/g), respectively. Both LDA and PLSR methods were proven to be effective in the discrimination/quantification of fungi contamination in peanuts. The results indicate that E-nose technology can be used as a feasible and reliable method for the determination of peanut quality during the storage, which can provide the theoretical reference for rapid detection of mold contamination during grain storage using volatile odor information. [ABSTRACT FROM AUTHOR]

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 × 104 to 3 × 105 colony-forming units (CFU) g−1. 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 Thermoascus and Thermomyces were detected, which could be key during composting. Moreover, the presence of several potentially harmful fungal species, such as Aspergillus fumigatus, A. terreus, and Scedosporium apiospermum, 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. [ABSTRACT FROM AUTHOR]