Comments on "Screening and identification of novel ochratoxin A-producing fungi from grapes. Toxins 2016,8,833" - in reporting ochratoxin A production from strains of Aspergillus, Penicillium and talaromcyes

Recently a species in the genus Talaromyces, a uniseriate species of Aspergillus section Nigri and an isolate each of two widespread species, Penicillium rubens and P. commune, were reported to produce ochratoxin A. This claim was based on insufficient biological and chemical data. We propose a list of criteria that need to be met before an unexpected mycotoxin producer is reported. There have only been convincing data on ochratoxin A production for Penicillium verrucosum, P. nordicum, P. thymicola, all from Penicillium series Verrucosa, and from species in three sections of Aspergillus: section Circumdati, section Nigri and section Flavi

Penicillium verrucosum occurrence and Ochratoxin A contents in organically cultivated grain with special reference to ancient wheat types and drying practice

This study addresses the relationship between the ochratoxigenic strains of Penicillium verrucosum and ochratoxin A (OTA) contents in organically cultivated grain. It included 37 combined, non-dried grain samples from farmers with no drying facilities as well as 19 non-dried and 22 dried samples from six farms with on-farm drying facilities (Case studies 1-6). The study focused on the ancient wheat type spelt but also included samples of wheat, rye, barley, oats, triticale, emmer, and einkorn. All 78 samples were analysed for moisture content (MC) and occurrence of P. verrucosum. The latter was assessed by plating non-disinfected kernels on DYSG agar and counting those contaminated by the fungus. Fiftyfive samples were analysed for OTA. Most of the combine harvested samples (82%) were contaminated with P. verrucosum prior to drying. This was ascribed to difficult harvest conditions and many samples of spelt, which was significantly more contaminated by P. verrucosum than oats, wheat and barley. Though not statistically significant, the results also indicated that spelt was more contaminated than rye, which is usually regarded the most sensitive small grain cereal. No correlation was found between number of kernels contaminated by P. verrucosum and OTA content. Despite many non-dried samples being contaminated by P. verrucosum, only two exceeded the EU maximum limit for grain (5 ng OTA g-1), both being spring spelt with 18 and 92 ng g-1, respectively. The problems were most likely correlated to a late harvest and high MC of the grain. The case studies showed exceedings of the maximum limit in a batch of dried oats and spring wheat, respectively, probably to be explained by insufficient drying of late harvested grain with high MC. Furthermore, our results clearly indicate that OTA is not produced in significant amounts in samples with MCs below 17%. All dried samples with MCs above 18% exceeded the 5 ng OTA g-1 limit in grain. However, no correlation between MC and the amount of OTA produced was found

The effect of culture preservation techniques on patulin and citrinin production by Penicillium expansum Link

Aims: To study the influence of culture preservation methods and culture conditions on the production of the mycotoxins patulin and citrinin by Penicillium expansum. Methods and results: Ten strains of Penicillium expansum were preserved using subculture and maintenance at 4 ºC, mineral oil, drying on silica gel and freeze-drying. Patulin and citrinin production was assessed on yeast extract sucrose agar (YES) and grape juice agar (GJ), using TLC before and after 0.5, 2–3, 6 and 12 months preservation. Citrinin was detected in all cultures for all preservation techniques on YES. The patulin profiles obtained differed with strain and culture media used. Conclusions: Citrinin production seems to be a stable character for the tested strains. There is a tendency for patulin detection with time apparently more consistent for silica gel storage and freeze-drying, especially when the strains are grown on GJ. Significance and Impact of the Study: Variability in the profiles of the mycotoxins tested seems to be more strain-specific than dependent on the preservation technique used

Effect of temperature and water activity on the production of fumonisins by Aspergillus niger and different Fusarium species

<p>Abstract</p> <p>Background</p> <p>Fumonisins are economically important mycotoxins which until recently were considered to originate from only a few <it>Fusarium </it>species. However recently a putative fumonisin gene cluster was discovered in two different <it>Aspergillus niger </it>strains followed by detection of an actual fumonisin B₂(FB₂) production in four strains of this biotechnologically important workhorse.</p> <p>Results</p> <p>In the present study, a screening of 5 <it>A. niger </it>strains and 25 assumed fumonisin producing <it>Fusarium </it>strains from 6 species, showed that all 5 <it>A. niger </it>strains produced FB₂and 23 of 25 <it>Fusarium </it>produced fumonisin B₁and other isoforms (fumonisin B₂and B₃). Five <it>A. niger </it>and five <it>Fusarium </it>spp. were incubated at six different temperatures from 15-42°C on Czapek Yeast Agar +5% salt or Potato Dextrose Agar. <it>A. niger </it>had the highest production of FB₂at 25-30°C whereas <it>Fusarium </it>spp. had the maximal production of FB₁and FB₂at 20-25°C. Addition of 2.5-5% NaCl, or 10-20% sucrose increased the FB₂production of <it>A. niger</it>, whereas addition of glycerol reduced FB₂production. All three water activity lowering solutes reduced the fumonisin production of the <it>Fusarium </it>species.</p> <p>Conclusion</p> <p>The present study shows that the regulation of fumonisin production is very different in <it>A. niger </it>and <it>Fusarium</it>, and that food and feeds preserved by addition of sugar or salts may be good substrates for fumonisin B₂production by <it>A. niger</it>.</p

Technologies for restricting mould growth on baled silage

End of project reportSilage is made on approximately 86% of Irish farms, and 85% of these make some baled silage. Baled silage is particularly important as the primary silage making, storage and feeding system on many beef and smaller sized farms, but is also employed as a secondary system (often associated with facilitating grazing management during mid-summer) on many dairy and larger sized farms (O’Kiely et al., 2002). Previous surveys on farms indicated that the extent of visible fungal growth on baled silage was sometimes quite large, and could be a cause for concern. Whereas some improvements could come from applying existing knowledge and technologies, the circumstances surrounding the making and storage of baled silage suggested that environmental conditions within the bale differed from those in conventional silos, and that further knowledge was required in order to arrive at a secure set of recommendations for baled silage systems. This report deals with the final in a series (O’Kiely et al., 1999; O’Kiely et al., 2002) of three consecutive research projects investigating numerous aspect of the science and technology of baled silage. The success of each depended on extensive, integrated collaboration between the Teagasc research centres at Grange and Oak Park, and with University College Dublin. As the series progressed the multidisciplinary team needed to underpin the programme expanded, and this greatly improved the amount and detail of the research undertaken. The major objective of the project recorded in this report was to develop technologies to improve the “hygienic value” of baled silage

Penicillium arizonense, a new, genome sequenced fungal species, reveals a high chemical diversity in secreted metabolites

A new soil-borne species belonging to the Penicillium section Canescentia is described, Penicillium arizonense sp. nov. (type strain CBS 141311(T) = IBT 12289(T)). The genome was sequenced and assembled into 33.7 Mb containing 12,502 predicted genes. A phylogenetic assessment based on marker genes confirmed the grouping of P. arizonense within section Canescentia. Compared to related species, P. arizonense proved to encode a high number of proteins involved in carbohydrate metabolism, in particular hemicellulases. Mining the genome for genes involved in secondary metabolite biosynthesis resulted in the identification of 62 putative biosynthetic gene clusters. Extracts of P. arizonense were analysed for secondary metabolites and austalides, pyripyropenes, tryptoquivalines, fumagillin, pseurotin A, curvulinic acid and xanthoepocin were detected. A comparative analysis against known pathways enabled the proposal of biosynthetic gene clusters in P. arizonense responsible for the synthesis of all detected compounds except curvulinic acid. The capacity to produce biomass degrading enzymes and the identification of a high chemical diversity in secreted bioactive secondary metabolites, offers a broad range of potential industrial applications for the new species P. arizonense. The description and availability of the genome sequence of P. arizonense, further provides the basis for biotechnological exploitation of this species

Interactive Global Illumination Effects Using Deterministically Directed Layered Depth Maps

A layered depth map is an extension of the well-known depth map used in rasterization. Multiple layered depth maps can be used as a coarse scene representation. We develop two global illumination methods which use said scene representation. The first is an interactive ambient occlusion method. The second is an interactive single-bounce indirect lighting method based on photon differentials. All of this is implemented in a rasterization-based pipeline

Identification of a Classical Mutant in the Industrial Host <i>Aspergillus niger</i> by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites

The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations