Description of a strain from an atypical population of Aspergillus parasiticus that produces aflatoxins B only, and the impact of temperature on fungal growth and mycotoxin production

In this study, an atypical strain of Aspergillus parasiticus is described. This strain, reported from Portuguese almonds, was named Aspergillus parasiticus B strain. The strain is herein characterised at the morphological and physiological levels, and compared with the typical A. parasiticus strain and other similar species in section Flavi. Previously published morphological and molecular data support that the B strain is very closely related to the A. parasiticus type strain. However, while A. parasiticus typically produces aflatoxins B and G, B strain produces aflatoxins B only. Furthermore, this atypical strain showed to differ from the typical strain in the fact that higher growth (colony diameter) and strain. This strain can become a major food safety concern in colder regions where the typical A. parasiticus strains are not well adapted.NORTE-07-0124-FEDER-000028PEst-OE/EQB/LA0023/2013PEst-OE/AGR/UI0690/201

Associations of passerine birds, rabbits, and ticks with <it>Borrelia miyamotoi and Borrelia andersonii</it> in Michigan, U.S.A.

<p>Abstract</p> <p>Background</p> <p>Wild birds contribute to maintenance and dissemination of vectors and microbes, including those that impact human, domestic animal, and wildlife health. Here we elucidate roles of wild passerine birds, eastern cottontail rabbits (<it>Sylvilagus floridanus</it>), and <it>Ixodes dentatus</it> ticks in enzootic cycles of two spirochetes, <it>Borrelia miyamotoi</it> and <it>B. andersonii</it> in a region of Michigan where the zoonotic pathogen <it>B. burgdorferi</it> co-circulates.</p> <p>Methods</p> <p>Over a four-year period, wild birds (n = 19,631) and rabbits (n = 20) were inspected for tick presence and ear tissue was obtained from rabbits. Samples were tested for <it>Borrelia</it> spirochetes using nested PCR of the 16S-23S rRNA intergenic spacer region (IGS) and bidirectional DNA sequencing. Natural xenodiagnosis was used to implicate wildlife reservoirs.</p> <p>Results</p> <p><it>Ixodes dentatus,</it> a tick that specializes on birds and rabbits and rarely bites humans, was the most common tick found, comprising 86.5% of the 12,432 ticks collected in the study. The relapsing fever group spirochete <it>B. miyamotoi</it> was documented for the first time in ticks removed from wild birds (0.7% minimum infection prevalence; MIP, in <it>I. dentatus</it>), and included two IGS strains. The majority of <it>B. miyamotoi</it>-positive ticks were removed from Northern Cardinals (<it>Cardinalis cardinalis</it>). <it>Borrelia andersonii</it> infected ticks removed from birds (1.6% MIP), ticks removed from rabbits (5.3% MIP), and rabbit ear biopsies (5%) comprised twelve novel IGS strains. Six species of wild birds were implicated as reservoirs for <it>B. andersonii.</it> Frequency of <it>I. dentatus</it> larval and nymphal co-feeding on birds was ten times greater than expected by chance. The relatively well-studied ecology of <it>I. scapularis</it> and the Lyme disease pathogen provides a context for understanding how the phenology of bird ticks may impact <it>B. miyamotoi</it> and <it>B. andersonii</it> prevalence and host associations.</p> <p>Conclusions</p> <p>Given the current invasion of <it>I. scapularis</it>, a human biting species that serves as a bridge vector for <it>Borrelia</it> spirochetes, human exposure to <it>B. miyamotoi</it> and <it>B. andersonii</it> in this region may increase. The presence of these spirochetes underscores the ecological complexity within which <it>Borrelia</it> organisms are maintained and the need for diagnostic tests to differentiate among these organisms.</p

Fungal community structure in disease suppressive soils assessed by 28S LSU gene sequencing

Natural biological suppression of soil-borne diseases is a function of the activity and composition of soil microbial communities. Soil microbe and phytopathogen interactions can occur prior to crop sowing and/or in the rhizosphere, subsequently influencing both plant growth and productivity. Research on suppressive microbial communities has concentrated on bacteria although fungi can also influence soil-borne disease. Fungi were analyzed in co-located soils 'suppressive' or 'non-suppressive' for disease caused by Rhizoctonia solani AG 8 at two sites in South Australia using 454 pyrosequencing targeting the fungal 28S LSU rRNA gene. DNA was extracted from a minimum of 125 g of soil per replicate to reduce the micro-scale community variability, and from soil samples taken at sowing and from the rhizosphere at 7 weeks to cover the peak Rhizoctonia infection period. A total of 994,000 reads were classified into 917 genera covering 54% of the RDP Fungal Classifier database, a high diversity for an alkaline, low organic matter soil. Statistical analyses and community ordinations revealed significant differences in fungal community composition between suppressive and nonsuppressive soil and between soil type/location. The majority of differences associated with suppressive soils were attributed to less than 40 genera including a number of endophytic species with plant pathogen suppression potentials and mycoparasites such as Xylaria spp. Non-suppressive soils were dominated by Alternaria, Gibberella and Penicillum. Pyrosequencing generated a detailed description of fungal community structure and identified candidate taxa that may influence pathogen-plant interactions in stable disease suppression