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Aspergillus flavus produces dangerous secondary metabolites known as aflatoxins, which are toxic and carcinogenic, and their contamination of agricultural products results in health issues and economic hardships in the U.S. and around the world. Early identification of aflatoxigenic isolates of A. flavus is the key in the management of these fungi. An emerging detection method for specific fungi identification involves the analysis of microbial volatile organic compounds (MVOCs) released by the fungi. Complicating this approach is the understanding that many factors influence metabolic production, including growth parameters, such as growth media, temperature, spore counts and oxidation stress. In addition, analytical and data analysis methods can also influence the results. Several growth and analysis methods were evaluated and optimized in order to better understand the effect of the methods on fungi MVOC signatures. The results indicate that carboxen/polydimethylsiloxane (CAR/PDMS) has the best extraction efficiency for the MVOCs emitted by A. flavus. Both chemical defined agar (CDA) and chemical defined liquid (CDL) are suitable growth media for MVOC emission studies. The highest MVOC production was found at 30˝C. Log transformation was considered one of the best data pretreatment methods when analyzing MVOC data and resulted in the best principal component analysis (PCA) clustering in the experiments with different growth media. This study aims to elucidate fungal volatile organic compounds (VOCs) differences due to variations in growth parameters as a first step in the development of an analytical method for the monitoring of aflatoxigenic A. flavus contamination in crop storage facilities.

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A study of the diversity and density of ectomycorrhizal (EM) fungi in two Fraser fir stands near Clingmans Dome, Great Smoky Mountains National Park was conducted over a period of three years. Plots were established in three naturally occurring age class treatments including mature tree, sapling, and low regeneration (no trees) sites. Lesser vegetation data were determined for nine plant species within all plots including two ferns and two grasses that impeded survival of Fraser fir seedlings. Diversity and densities of vegetation were significantly greater in low regeneration plots as compared to other treatments. For each plot bryophyte mat forest floor percent occurrence/cover was obtained and percent root colonization/sclerotia of the EM fungus taxa were collected from the three management treatments including 11 decomposers and 33 ectomycorrhizal species. Clavulina cristata occurred in 22.5% of all plots and had a frequency of 1.7% in low regeneration treatments. Four species of Laccaria occurred in Fungi 9(1): 1-21 17.3% of all plots, and Laccaria laccata and L. laccata var. pallidifolia were the most common of these species, the former having the highest frequency of occurrence (1.9%) in low regeneration treatments. Four species of Cortinarius occurred in 10.3% of the plots, and Cortinarius anomalus s.l., the most common Cortinarius, occurred in 4.4% of all plots. Seven of the 44 species had significantly greater percent frequency among the three treatments, and six of those were the most frequent in sapling plot treatments at the two locations. Species found at the two locations were similar, although in 2009 their frequency values were greater than in 2010 and 2011 due to greater total precipitation. Mature and sapling plot frequency values were significantly greater than those for low regeneration sites due to the low establishment of Fraser fir. Significant results for species richness, diversity and evenness between years, locations and treatments are present below. Based on percent frequency values, Laccaria could be used in reforestation of Fraser firs in all plots. A project is underway to evaluate seedling establishment and survival following inoculation with Laccaria spp. on a low regeneration site at Mount Buckley.2 Baird et al. Diversity and density of EM Fungi in high elevation Fraser fir. North American