Modelling a two-dimensional spatial distribution of mycotoxin concentration in bulk commodities to design effective and efficient sample selection strategies

Mycotoxins in agricultural commodities are a hazard to human and animal health. Their heterogeneous spatial distribution in bulk storage or transport makes it particularly difficult to design effective and efficient sampling plans. There has been considerable emphasis on identifying the different sources of uncertainty associated with mycotoxin concentration estimations, but much less on identifying the effect of the spatial location of the sampling points. This study used a two-dimensional statistical modelling approach to produce detailed information on appropriate sampling strategies for surveillance of mycotoxins in raw food commodities. The emphasis was on deoxynivalenol (DON) and ochratoxin A (OTA) in large lots of grain in storage or bulk transport. The aim was to simulate a range of plausible distributions of mycotoxins in grain from a set of parameters characterising the distributions. For this purpose, a model was developed to generate data sets which were repeatedly sampled to investigate the effect that sampling strategy and the number of incremental samples has on determining the statistical properties of mycotoxin concentration. Results showed that, for most sample sizes, a regular grid proved to be more consistent and accurate in the estimation of the mean concentration of DON, which suggests that regular sampling strategies should be preferred to random sampling, where possible. For both strategies, the accuracy of the estimation of the mean concentration increased significantly up to sample sizes of 40-60 (depending on the simulation). The effect of sample size was small when it exceeded 60 points, which suggests that the maximum sample size required is of this order. Similar conclusions about the sample size apply to OTA, although the difference between regular and random sampling was small and probably negligible for most sample sizes

Impact of environmental factors on growth and satratoxin G production by strains of Stachybotrys chartarum

The black mould Stachybotrys chartarum and its mycotoxins have been linked to damp building-associated illnesses. The objective of this study was to determine the effects of water availability (water activity, aw) and temperature on growth and production of satratoxin G (SG) by a macrocyclic trichothecene-producing strain (IBT 7711) and non-producing strain (IBT 1495) of S. chartarum. Growth studies were carried out on potato dextrose agar modified with glycerol to 0.995-0.92 aw at 10-37 °C. Growth extension was measured and the cultures were extracted after 10 days and a competitive enzyme-linked immunosorbent assay (ELISA) method used to quantify the SG content. Growth was optimal at 25 to 30 °C at 0.995 aw, but this was modified to 0.98 aw at 30 °C for both strains (1.4- 1.6 mm/day, respectively). The ELISA method revealed that, in contrast to growth, SG production was maximal at 20 °C with highest production at 0.98 aw (approximately 250 μg/g mycelia). When water was freely available (0.995 aw), SG was maximally produced at 15 °C and decreased as temperature was increased. Interestingly, the strain classified as a non-toxigenic produced very low amounts of SG (<1.6 μg/g mycelia) that were maximal at 25 °C and 0.98 aw. Contour maps for growth and SG production were developed from these data sets. These data have shown, for the first time, that growth and SG production profiles are very different in relation to key environmental conditions in the indoor environment. This will be very useful in practically determining the risk from exposure to S. chartarum and its toxins in the built env

Safe food and feed through an integrated toolbox for mycotoxin management: the MyToolBox approach

There is a pressing need to mobilise the wealth of knowledge from the international mycotoxin research conductedover the past 25-30 years, and to perform cutting-edge research where knowledge gaps still exist. This knowledgeneeds to be integrated into affordable and practical tools for farmers and food processors along the chain inorder to reduce the risk of mycotoxin contamination of crops, feed and food. This is the mission of MyToolBox – a four-year project which has received funding from the European Commission. It mobilises a multi-actorpartnership (academia, farmers, technology small and medium sized enterprises, food industry and policystakeholders) to develop novel interventions aimed at achieving a significant reduction in crop losses due tomycotoxin contamination. Besides a field-to-fork approach, MyToolBox also considers safe use options ofcontaminated batches, such as the efficient production of biofuels. Compared to previous efforts of mycotoxin reduction strategies, the distinguishing feature of MyToolBox is to provide the recommended measures to theend users along the food and feed chain in a web-based MyToolBox platform (e-toolbox). The project focuseson small grain cereals, maize, peanuts and dried figs, applicable to agricultural conditions in the EU and China. Crop losses using existing practices are being compared with crop losses after novel pre-harvest interventionsincluding investigation of genetic resistance to fungal infection, cultural control (e.g. minimum tillage or cropdebris treatment), the use of novel biopesticides suitable for organic farming, competitive biocontrol treatment and development of novel modelling approaches to predict mycotoxin contamination. Research into post-harvestmeasures includes real-time monitoring during storage, innovative sorting of crops using vision-technology, novelmilling technology and studying the effects of baking on mycotoxins at an industrial scale

The influence of ecophysiological factors on growth, aflR gene expression and aflatoxin B1 production by a type strain of Aspergillus flavus

Maize is prone to infection by Aspergillus flavus, which can contaminate the product with aflatoxins. The objective of this study was to examine the impact that interactions between water activity (aw) and temperature may have on growth, the expression of a biosynthetic regulatory gene (aflR) and aflatoxin B1 (AFB1) production by a strain of A. flavus on a maize-based medium. Results showed that there were some differences between lag phases and growth rates of A. flavus. The optimum growth rate for A. flavus was at 30 °C and 0.99 aw. No growth occurred at 0.90 aw and 20 °C. Both temperature and aw had an influence on the relative aflR gene expression and AFB1 production by A. flavus; however, the results for AFB1 production were not consistent with the effects on gene expression or growth. These findings provide data that are useful to better understand the conditions which represent higher risks from AFB1 production. However, the aflR expression was not a good indicator of AFB1 production alone. Thus, further molecular studies of other AF-related genes should be done. These results are discussed in the context of harvesting and storage of maize and the prevailing environmental conditions to minimise AFB1 contamination

Advances in molecular and genomic research to safeguard food and feed supply from aflatoxin contamination

Worldwide recognition that aflatoxin contamination of agricultural commodities by the fungus Aspergillus flavus is a global problem has significantly benefitted from global collaboration for understanding the contaminating fungus, as well as for developing and implementing solutions against the contamination. The effort to address this serious food and feed safety issue has led to a detailed understanding of the taxonomy, ecology, physiology, genomics and evolution of A. flavus, as well as strategies to reduce or control pre-harvest aflatoxin contamination, including (1) biological control, using atoxigenic aspergilli, (2) proteomic and genomic analyses for identifying resistance factors in maize as potential breeding markers to enable development of resistant maize lines, and (3) enhancing host-resistance by bioengineering of susceptible crops, such as cotton, maize, peanut and tree nuts. A post-harvest measure to prevent the occurrence of aflatoxin contamination in storage is also an important component for reducing exposure of populations worldwide to aflatoxins in food and feed supplies. The effect of environmental changes on aflatoxin contamination levels has recently become an important aspect for study to anticipate future contamination levels. The ability of A. flavus to produce dozens of secondary metabolites, in addition to aflatoxins, has created a new avenue of research for understanding the role these metabolites play in the survival and biodiversity of this fungus. The understanding of A. flavus, the aflatoxin contamination problem, and control measures to prevent the contamination has become a unique example for an integrated approach to safeguard global food and feed safety

Retinal thickness measurements in sickle cell patients with HbSS and HbSC genotype

OBJECTIVE: Temporal macula thinning has been reported in sickle cell patients, but it remains unclear if there is a difference between HbSS and HbSC genotypes. We aimed to quantitatively compare macular thickness between eyes with HbSS and HbSC genotype. DESIGN: Retrospective descriptive study. METHODS: Consecutive patients seen over a 5.5-year period in the Ophthalmology Department at St Thomas’ Hospital, London, were identified. Macular optical coherence tomography images were retrospectively analyzed. The retinal thickness in all 9 subfields of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid was compared between HbSS and HbSC eyes. Right eyes and left eyes were analyzed independently, as well as averaged measurements from both eyes. Comparison was made between the 2 genotypes, adjusting for age and sex, and for multiple testing. Scans were excluded in cases of poor fixation or ocular comorbidity affecting retinal thickness. RESULTS: 132 HbSC and 120 HbSS patients were identified. Scans from 166 right and 153 left eyes were included (with approximately equal numbers of HbSS and HbSC genotypes). Mean retinal thickness was lower in HbSS eyes compared with HbSC eyes in all subfields of the ETDRS grid, but in most subfields the difference was <10 microns. Differences reached statistical significance for outer superior, inferior, and temporal subfields and the inner temporal subfield (p < 0.05). CONCLUSION: Although the HbSC genotype is more strongly associated with proliferative retinopathy, HbSS patients had on average more macular thinning

Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA‐1 on grapes

Biocontrol agents have become componentsof integrated crop protection systemsfor controlling economically important fungal pathogens.Candida sakeCPA-1 is abiocontrol agent of fungal pathogens of fruits, both pre- and post-harvest. Whilethe efficacy of different formulations have been examined previously, few studieshave considered the resilience of different formulations under changing climaticconditions of elevated temperature, drought stress and increased atmospheric CO2.This study examined the effect of (a) temperature9RH9elevated CO2(400vs1000 ppm) on the temporal establishment and viability of two dry and one liquidC. sakeCPA-1 formulations on grape berry surfaces; (b) temperature stress (25vs35°C); and (c) elevated CO2levels. Results indicated that temperature, RH and CO2concentration influenced the establishment and viability of the formulations butthere was no significant difference between formulations. For the combined three-component factors, increased temperature (35°C) and lower RH (40%) reduced theviable populations on grapes. The interaction with elevated CO2improved theestablishment of viable populations of the formulations tested. Viable populationsgreater than Log 4 CFUs per g were recovered from the grape surfaces suggestingthat these had conserved resilience for control ofBotrytisrot in grapes.info:eu-repo/semantics/acceptedVersio

Proof of concept: could snake venoms be a potential source of bioactive compounds for control of mould growth and mycotoxin production

© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The objective was to screen 10 snake venoms for their efficacy to control growth and mycotoxin production by important mycotoxigenic fungi including Aspergillus flavus, Aspergillus westerdijkiae, Penicillium verrucosum, Fusarium graminearum and F. langsethiae. The Bioscreen C rapid assay system was used. The venoms from the Viperidae snake family delayed growth of some of the test fungi, especially F. graminearum and F. langsethiae and sometimes A. flavus. Some were also able to reduce mycotoxin production. The two most potent crude snake venoms (Naja nigricollis and N. siamensis; 41 and 43 fractions, respectively) were further fractionated and 83/84 of these fractions were able to reduce mycotoxin production by >90% in two of the mycotoxigenic fungi examined. This study suggests that there may be significant potential for the identification of novel fungistatic/fungicidal bioactive compounds as preservatives of raw and processed food commodities post-harvest from such snake venoms.Peer reviewedFinal Published versio

Predicted ecological niches and environmental resilience of different formulations of the biocontrol yeast Candida sake CPA-1 using the Bioscreen C

Environmental resilience of biocontrol microorganisms has been a major bottleneck in the development of effective formulations. Candida sake is an effective biocontrol agent (BCA) against Penicillium expansum, Botrytis cinerea or Rhizopus stolonifer, and different formulations of the BCA have been optimised recently. The objective of this study was to compare the relative tolerance of different dry and liquid formulations of the biocontrol yeast C. sake CPA-1 to interacting environmental conditions using the Bioscreen C. Initially, the use of this automated turbidimetric method was optimised for use with different formulations of the biocontrol yeast. The best growth curves were obtained for the C. sake CPA-1 strain when grown in a synthetic grape juice medium under continuous shaking and with an initial concentration of 105 CFUs ml−1. All the formulations showed a direct relationship between optical density values and yeast concentrations. Temperature (15–30 °C) and water activity (aw; 0.94–0.99) influenced the yeast resilience most profoundly, whereas the effect of pH (3–7) was minimal. In general, the liquid formulation grew faster in more interacting environmental conditions but only the yeast cells in the dry potato starch formulation could grow in some stress conditions. This rapid screening method can be used for effective identification of the resilience of different biocontrol formulations under interacting ecological abiotic conditions.info:eu-repo/semantics/acceptedVersio

Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA‐1 on grapes

Biocontrol agents have become components of integrated crop protection systems for controlling economically important fungal pathogens. Candida sake CPA‐1 is a biocontrol agent of fungal pathogens of fruits, both pre‐ and post‐harvest. While the efficacy of different formulations have been examined previously, few studies have considered the resilience of different formulations under changing climatic conditions of elevated temperature, drought stress and increased atmospheric CO2. This study examined the effect of (a) temperature × RH × elevated CO2 (400 vs 1000 ppm) on the temporal establishment and viability of two dry and one liquid C. sake CPA‐1 formulations on grape berry surfaces; (b) temperature stress (25 vs 35°C); and (c) elevated CO2 levels. Results indicated that temperature, RH and CO2 concentration influenced the establishment and viability of the formulations but there was no significant difference between formulations. For the combined three‐component factors, increased temperature (35°C) and lower RH (40%) reduced the viable populations on grapes. The interaction with elevated CO2 improved the establishment of viable populations of the formulations tested. Viable populations greater than Log 4 CFUs per g were recovered from the grape surfaces suggesting that these had conserved resilience for control of Botrytis rot in grapes