Harmful Secondary Metabolites Research Articles

PSVI-20 Trends in Mycotoxin Contamination of the 2022 United States Corn Crop

Abstract Mycotoxins are harmful secondary fungal metabolites detrimental to animal health, even at reduced quantities. Focus on clinical signs such as decreased feed intake and vomiting overlook impacts of mycotoxicosis, including increased disease incidence and severity, immune modulation, inflammation, and gastrointestinal disorders. This study was conducted to compare mycotoxin contamination of initial samples of the 2022 corn crop with previous year trends. Samples were analyzed utilizing the liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for six major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A (OTA). The 2022 crop year data were compared with the prior four harvest years using GLIMMIX procedure of SAS with harvest year as fixed effect and sample as the experimental unit. A limited number of samples is available thus far (n = 44) as harvest is still progressing, therefore the risk profile of this crop year is likely to change as the sample pool expands. Contamination levels in corn for the tested toxin groups have remained consistent over the survey period. To date, 97% of the samples evaluated contained at least one mycotoxin, compared with 90% that was observed in 2021. The percentage of Afla contaminated samples increased (P < 0.05) in 2022 corn compared with the 2020 and 2021 harvest years (42 vs. 5 and 7%). The percentage of FUM contaminated samples in 2022 corn is greater (P < 0.05) compared with 2020 and 2021 (88 vs. 64 and 64%). The preliminary results of the 2022 US corn crop survey indicate mycotoxin occurrence and contamination levels are similar or greater (Afla and FUM) to the prior crop year and will continue to challenge animal health and performance as these ingredients are fed out.

Limits of Detection Determination of Aflatoxin B1 using the Optical Waveguide Lightmode Spectroscopy via the Four-Parameter Logistic Model

Mycotoxins are harmful secondary metabolites generated by a variety of fungi, and they may be found in a vast array of food and feed commodities and processed meats from animals fed infected meal. Numerous mycotoxins are extremely resistant and survive food processing, entering the food chain and posing a concern to human health. The "optical waveguide lightmode spectroscopy" (OWLS) method was used to detect aflatoxin B1 in plant sample matrices. The calibration curve for the detection of aflatoxin B1 utilizing "optical waveguide lightmode spectroscopy" (OWLS) displayed a sigmoidal shape; hence, the 5-PL or 4-PL model should be used to fit the data rather than a linear model. Using error function analysis with functions such as AICc, HQC, BIC, RMSE, adjR2, Bias Factor, and Accuracy Factor, the 5-PL and 4-Pl models are distinguished inconsistently. The overlapping confidence intervals of the LogEC50 values suggested that the two techniques did not differ much, and the 4-PL model was selected due to its smaller number of parameters. The Limits of Detection for aflatoxin B1 value based on the 4-PL equation was 8.787 ng/mL with the 95% confidence interval from 5.728 to 13.100. In this study, the use of the 4-PL model was successful and was able to represent the entire date curve, not only the linear section. The linear component is crucial as a handy and swift approach for assessing the sensitivity of a developed biosensor technology and is often a more beneficial method for field applications when a quick and straightforward evaluation is required.

Phytosphingosine-induced cell apoptosis via a mitochondrially mediated pathway

Cyanobacterial blooms, usually dominated by Microcystis aeruginosa, pose a serious threat to global freshwater ecosystems owing to their production and release of various harmful secondary metabolites. Detection of the chemicals in M. aeruginosa exudates using metabolomics technology revealed that phytosphingosine (PHS) was one of the most abundant compounds. However, its specific toxicological mechanism remained unclear. CNE-2 cells were selected to illustrate the cytotoxic mechanism of PHS, and it was determined to cause excessive production of reactive oxygen species and subsequently damage the mitochondrial structure. Mitochondrial membrane rupture led to matrix mitochondrial membrane potential disintegration, which induced Ca2+ overload and interrupted ATP synthesis. Furthermore, rupture of the mitochondrial membrane induced the opening of the permeability transition pore, which caused the release of proapoptotic factors into the cytoplasm and the expression of apoptosis-related proteins Bax, Bcl-2, cytochrome-c and cleaved caspase-3 in CNE-2 cells. These events, in turn, activated the mitochondrially mediated intrinsic apoptotic pathway. A mitochondrial repair mechanism, namely, PINK1/Parkin-mediated mitophagy, was then blocked, which further promoted apoptosis. Our findings suggest that more attention should be paid to the ecotoxicity of PHS, which is already listed as a contaminant of emerging concern.

Adsorbents Used for Microcystin Removal from Water Sources: Current Knowledge and Future Prospects

The increasing occurrence of toxic cyanobacteria in water sources, driven by climate change and eutrophication, is of great concern worldwide today. Cyanobacterial blooms can negatively affect water bodies and generate harmful secondary metabolites, namely microcystins (MCs), which significantly impair water quality. Various adsorbents used for MC removal from water sources were assessed in this investigation. Activated carbon constitutes the most widely used adsorbent for treating contaminated waters due to its high affinity for adsorbing MCs. Alternative adsorbents have also been proposed and reported to provide higher efficiency, but the studies carried out so far in this regard are still insufficient. The mechanisms implicated in MC adsorption upon different adsorbents should be further detailed for a better optimization of the adsorption process. Certainly, adsorbent characteristics, water pH and temperature are the main factors influencing the adsorption of MCs. In this context, optimization studies must be performed considering the effectiveness, economic aspects associated with each adsorbent. This review provides guidelines for more practical field applications of the adsorption in the treatment of waters actually contaminated with MCs.

PSV-16 Recent Mycotoxin Contamination Trends in 2021 United States Corn

Abstract Mycotoxins are harmful secondary fungal metabolites detrimental to animal health even at low levels. The study was conducted to compare mycotoxin contamination of initial samples of the 2021 corn crop with previous year trends. Samples were analyzed utilizing the liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for 6 major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A (OTA). The 2021 corn crop year data were compared with the prior harvest years using GLIMMIX procedure of SAS with harvest year as fixed effect and sample as the experimental unit. A limited number of samples is available thus far (n = 44) as harvest is still progressing, therefore the risk profile of this crop year is likely to change as the sample pool expands. To date, 100% of the samples evaluated contained at least one mycotoxin, compared with 87% that was observed in 2020. The FUM is the most prevalent mycotoxin group (80% positive in 2021 vs. 49% in 2020) with average contamination level 5,883 ppb, which is significantly (P < 0.05) greater than the 2019 and 2020 harvested corn (3,348 ppb and 2,783 ppb, respectively). Contamination levels in corn for Afla, A-Trich, B-Trich, ZEN, and OTA have remained consistent over the survey period. The percentage of B-Trich and ZEN contaminated samples are numerically decreased in 2021 compared with 2020 (B-Trich: 59% vs. 50%; ZEN: 20% vs. 11%), whereas Alfa contaminated corn has increased numerically (5% vs. 23%). The preliminary results of the 2021 corn crop survey indicate mycotoxin occurrence and contamination levels are similar or greater (FUM) to the prior crop year and will continue to challenge animal health and performance as these ingredients are fed out.

Potential influence of overwintering benthic algae on water quality

Overwintering benthic algae not only directly impact drinking water safety, but also affect the algae recruitment in warm spring seasons. Thus, understanding the characteristics of overwintering benthic algae can provide scientific references for formulating preventative strategies of reasonable water resource. However, they have received less attention. In this study, the spatiotemporal variation of benthic algae and their harmful secondary metabolites were studied from autumn to summer in Qingcaosha Reservoir. Benthic algae (picophytobenthos accounting for 55.42%) had a high biomass during overwintering, and the groups of overwintering benthic algae included pico-Cyanobacteria, pico-Cryptomonas, pico-Chlorophyta, pico-Diatoms, Cyanobacteria, Chlorophyta, Cryptomonas and Diatoms, which were consistent with the planktonic algae species in warm seasons. In oligotrophic or mesotrophic water bodies, micronutrients of iron and manganese were key nutrient factors influencing the biomass of benthic algae. Furthermore, picophytobenthos were important potential contributors of harmful secondary metabolites. The content of microcystins, anatoxin-a, geosmin and 2-methylisoborneol in sediment were 15.75 µg/kg·FW, 48.16 µg/kg·FW, 3.91 ng/kg·FW, and 11.76 ng/kg·FW during winter, which had potential to be released into water bodies to impact water quality. These findings indicate that water quality monitoring programs need to consider sediment in winter as a potential source of toxins and preventative measures to prevent excessive proliferation of algae should be implemented in winter.

336 Occurrence of Mycotoxins in 2020 US Pasture Grasses and Harvested Hay Feed Ingredients

Abstract Mycotoxins are harmful secondary fungal metabolites which limit animal health and performance through various negative effects such as reduced feed intake, diarrhea, and compromised immune and reproductive function. These metabolites are found in a variety of feedstuffs worldwide. This study monitored mycotoxin occurrence and contamination levels in fresh pasture grasses and harvested dry hay from across the US. Samples were screened for six major mycotoxin groups: aflatoxins, type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin A via LC-MS/MS. Samples that were above the limit of detection for each mycotoxin group were analyzed using the GLIMMIX procedure of SAS (SAS 9.4, Cary, NC) to test the effect of harvest year on average contamination level. Results are presented in Table 1. Zearalenone and B-Trich contamination prevalence for fresh grass samples was lower in 2020 compared to the previous two years. A-Trich tested positive in 34% of samples which was greater in 2020 compared to 2018 and 2019. Mean concentration levels (parts per billion, ppb) for B-Trich, ZEN, A-Trich were not different in 2020 compared to the previous two years. Prevalence of mycotoxin contamination for dry harvested hay samples for B-Trich and ZEN decreased in 2020 compared to the previous two years, but 64 and 28% of samples tested positive, respectively. A-Trich prevalence was greater than the last two years and resulted in 17% of samples testing positive compared to 0 and 6% in 2018 and 2019, respectively. Mean B-Trich levels in 2020 were similar to levels seen in 2018 and lower than 2019 (P = 0.005). Mean ZEN and A-Trich concentration levels averaged 1,612 ppb and 796 ppb, respectively. Mycotoxin analysis of pasture grasses and harvested hay forages is warranted to identify potential sources of mycotoxin contamination in ruminant diets.

Photorhabdus sp. ETL Antimicrobial Properties and Characterization of Its Secondary Metabolites by Gas Chromatography–Mass Spectrometry

Entomopathogenic nematodes (EPNs) are known to be highly pathogenic to insect pests, due to their associated symbiotic bacteria, which produce virulence factors, exo-enzymes and other harmful secondary metabolites to conquer, kill, and degrade their insect hosts. However, these properties are not fully characterized. This study reports on the antimicrobial activities of Photorhabdus sp. strain ETL, symbiotically associated to an insect pathogenic nematode, Heterorhabditis zealandica, against human pathogenic bacteria and toxigenic fungi, as well as the non-targeted profiling of its secondary metabolites (SMs) using gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Fatty acids including 3-eicosene, (E)-; 5-eicosene, (E)-; eicosene; 9-octadecenamide; undecanoic acid with shown antimicrobial activities were detected. This provided more insight on the composition and bioactivities of SMs produced by the Photorhabdus sp.

136 Mycotoxin Contamination in United States Corn and Corn DDGS from 2019 and 2020 Harvest

Abstract Mycotoxins are harmful secondary fungal metabolites central to food and feed safety management. These toxins are detrimental to animal health and even at low levels can compromise performance. Focus on clinical signs like decreased feed intake and vomiting overlook significant impacts of mycotoxicosis, including increased disease incidence and severity, immune dysfunction, inflammation, and modulation of the gastrointestinal environment. The objective of this study was to determine the effect of harvest year on five major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), and zearalenone (ZEN) in corn and corn DDGS samples. For each mycotoxin group within ingredient, 2019 harvest (329 corn and 20 corn DDGS) were compared with 2020 harvest (27 corn and 21 corn DDGS). Data were analyzed using GLIMMIX procedure of SAS with harvest year as fixed effect and sample as the experimental unit. Average B-Trich and FUM contamination levels in corn are significantly (P < 0.05) affected by harvest year. However, B-Trich levels remained consistent, whereas FUM decreased (P < 0.05) from 2019 to 2020. Contamination levels in corn for Afla, A-Trich, and ZEN have remained consistent (P > 0.05) from 2019 to 2020. In corn DDGS, B-Trich contamination level was decreased (P < 0.05) from 2019 to 2020, whereas FUM and ZEN contamination levels remained similar (P > 0.05). The 2020 crop risk profile is likely to change as the sample pool expands. A combination of hot weather, storm events, and drought during the 2020 growing season resulted in crop stress and damage, ultimately leading to grain quality and mycotoxin contamination concerns. Due to the continued risk of mycotoxin co-occurrence, expanding mitigation strategies beyond adsorption by mycotoxin deactivation with biotransformation and additional support of immune and liver function is essential.

About the significance of the fungal genus Alternaria for the food sector: plant pathogens and mycotoxins

The fungal infestation of agricultural crops worldwide leads to considerable economic losses every year. Moreover, certain major plant pathogens like Alternaria species produce harmful secondary metabolites, so-called mycotoxins, which may result in food contamination and therefore a potential health risk for consumers. Data on the occurrence and the toxicological potential of the “emerging” Alternaria toxins are still scarce, which limits comprehensive risk assessments. Here, we present a summary of current Alternaria research focusing on the development of innovative analytical tools to determine contamination patterns in various food products and the investigations of metabolic defense strategies in plants and mammals (biotransformation). By the application of sophisticated LC-MS-based multi-toxin quantitation methods, barely studied toxins and even biologically modified toxins were revealed to contribute considerable concentrations to the overall exposure. Furthermore, in vivo studies gave intriguing first insights in bioavailability, metabolism, and excretion rates of Alternaria toxins in rats. These valuable data set demonstrates the necessity for further studies to approach the question, whether legal regulations of Alternaria toxins would be appropriate to continuously ensure and increase food safety.

Pre-Harvest Modelling and Mitigation of Aflatoxins in Maize in a Changing Climatic Environment-A Review.

Aflatoxins (AFs) are harmful secondary metabolites produced by various moulds, among which Aspergillus flavus is the major AF-producer fungus. These mycotoxins have carcinogenic or acute toxigenic effects on both humans and food producing animals and, therefore, the health risks and also the potential economic damages mounted by them have led to legal restrictions, and several countries have set maximum allowable limits for AF contaminations in food and feed. While colonization of food and feed and AF production by A. flavus are highly supported by the climatic conditions in tropical and subtropical geographic regions, countries in the temperate climate zones are also increasingly exposed to AF-derived health risks due to climate change. In the present study, we have reviewed the available mathematical models as risk assessment tools to predict the possibility of A. flavus infection and levels of AF contaminations in maize in a changing climatic environment. After highlighting the benefits and possible future improvements of these models, we summarize the current agricultural practices used to prevent or, at least, mitigate the deleterious consequences of AF contaminations

PSII-22 Trends in Mycotoxin Contamination in United States Corn

Abstract Mycotoxins are harmful secondary fungal metabolites and are of key concern to food and feed safety globally. These toxins are detrimental to animal health and can compromise animal performance even at low levels. Classic signs such as decreased feed intake and vomiting used as indicators for exposure overlook other costs of mycotoxicosis, including increasing the frequency and severity of disease via immune suppression, inciting inflammation, and modulating the gastrointestinal environment. This survey examines initial samples of the 2019 crop with previous year trends. New crop corn samples were submitted from September 2019 and consisted of corn (46%), corn silage (50%), and corn byproduct (4%). Samples were analyzed utilizing the liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for six major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin-A (OTA). Data are presented for major mycotoxin classes in Table 1. Fewer samples are available thus far compared to the fall of 2018 (50 samples in 2019 vs. 135 samples in 2018), thus risk profile of this crop year is likely to change as the sample pool expands. Co-occurrence (≥ 2 mycotoxins) has decreased compared to 2018. The prevalence of B-Trich decreased compared with previous years, but levels are similar to 2018. Prevalence and levels of ZEN decreased from 2018, and are similar to 2017, while FUM is similar in prevalence to 2018, but average ppb numerically increased. As of yet, no Alfa has been detected; however, corn stored with higher moisture content has increased the risk for storage toxins. Mycotoxin risk of this harvest season is still coming into focus as harvest delays have affected sample submission. Due to continued risk of multi-mycotoxin contamination, multiple mitigation strategies are needed beyond just adsorption, including biotransformation, support of the immune system and liver function.

Toward Disentangling the Multiple Nutritional Constraints Imposed by Planktothrix: The Significance of Harmful Secondary Metabolites and Sterol Limitation.

The harmful bloom-forming cyanobacterium Planktothrix is commonly considered to be nutritionally inadequate for zooplankton grazers, resulting in limited top-down control. However, interactions between Planktothrix and zooplankton grazers are poorly understood. The food quality of Planktothrix is potentially constrained by morphological properties (i.e., filament formation), the production of harmful secondary metabolites, and a deficiency in essential lipids (i.e., primarily sterols). Here, we investigated the relative significance of toxin production (microcystins, carboxypeptidase A inhibitors, protease inhibitors) and sterol limitation for the performance of Daphnia feeding on one Planktothrix rubescens and one P. agardhii wild-type/microcystin knock-out mutant pair. Our data suggest that the poor food quality of both Planktothrix spp. is due to deleterious effects mediated by various harmful secondary metabolites and that the impact of sterol limitation is partially or completely superimposed by toxicity. The significance of the different factors seems to depend on the metabolite profile of the considered Planktothrix strain and the Daphnia clone that is used for the experiments. The toxin-responsive gene expression (transporter genes, gpx, and trypsin) and enzyme activity patterns revealed strain-specific food quality constraints and that Daphnia is capable of modulating its physiological responses according to the ingested Planktothrix strain. Future studies need to consider that Planktothrix–grazer interactions are simultaneously modulated by multiple factors to improve our understanding of top-down influences on Planktothrix bloom formation.

Co-occurrence of microcystin- and geosmin-producing cyanobacteria in the Tri An Reservoir, a drinking-water supply in Vietnam

The present study aimed to investigate the occurrence and distribution of microcystin-(MC) and geosmin-producing cyanobacteria in the Tri An Reservoir, a drinking-water supply in Southern Vietnam. The MC concentration was measured using high-performance liquid chromatography (HPLC). Geosmin production was screened using headspace solid-phase microextraction (HPME) and gas chromatography/mass spectrometry (GC/ MS). The ability of cyanobacteria to produce MC and geosmin was determined by the presence of two molecular markers: mcyA and geoA, respectively. A maximum MC concentration of 207.6 ± 14.2 μg g –1 dry weight (DW) was detected from an isolated Microcystis aeruginosa (Kützing) (strains TAMA1), and the maximum geosmin concentration of 114.2 ± 6.1 ng g –1 wet weight (WW) was detected from an isolated Dolichospermum circinale (Rabenhorst) (strains TADC4); MC and geosmin were also observed in water-bloom samples, with the highest concentrations being 463.6 ± 34.7 μg g –1 DW and 148.5 ± 9.8 ng g –1 WW, respectively. These results represent the first molecular evidence of the co-occurrence of MC- and geosmin-producing cyanobacteria in a drinking-water-supply reservoir in Vietnam. Given the success of the molecular techniques and chemical analysis used, we propose that multiplex polymerase chain reaction assays, HPLC, and HPME GC/MS can be reliable tools for investigating MC and geosmin in water-bloom and cyanobacterial samples. Further, we propose that they can be used to create early-warning systems for harmful secondary metabolites produced by cyanobacteria in drinking-water supplies.

359 Occurrence of mycotoxins in 2018 us corn-based feed ingredients

Abstract Mycotoxins are harmful secondary fungal metabolites that are detrimental to animal health and productivity. This study investigated occurrence and contamination levels of mycotoxins in the 2018 US corn harvest including corn grain, corn silage and corn by-product feed ingredients (distillers dried grains, gluten feed, etc.). Corn and corn silage samples marked as 2018 harvest from feed mills, livestock producers, and integrators and corn DDGS and other by-products from mid-August 2018 through January 2019 were screened via the LC-MS/MS technique for the presence of six major mycotoxin groups: aflatoxins, type A trichothecenes, type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN) and ochratoxin. Parameters of the main toxins found were compared to the two prior harvest years using the Kruskal-Wallis Test (Prism7, GraphPad, La Jolla, CA) and are presented in Table 1. Mean toxin count per sample in corn grain increased in 2018 versus 2017, returning to over two toxins per sample as in 2016. Mean B-Trich level (ppb) is elevated in 2018 from 2017. Although ZEN contamination does not differ from prior years, prevalence increased to 45% from 25% in 2017. Co-contamination in corn by-product feeds is steady, averaging nearly three toxins per sample. Mean B-Trich is higher than the 2017 crop, while FUM contamination is similar to 2017. ZEN levels in 2018 by-products are the highest seen in the past three years. Corn silage has increased in mean toxin count per sample and contamination levels of B-Trich and ZEN in 2018 versus 2017. Prevalence of B-trich has remained constant from year to year, while both ZEN and FUM prevalence have increased from 2017 to 2018. Preliminary results of the 2018 corn-based feed ingredients survey suggest mycotoxin occurrence and contamination levels are approaching those observed in the challenging 2016 crop with continued concerns for co-contamination.

10 Occurrence of mycotoxins in wheat middlings

Abstract Mycotoxins are harmful secondary fungal metabolites which can contaminate a variety of feedstuffs worldwide. Various negative effects in vivo are associated with these toxins and severity is dependent on the level, type, and duration of exposure and age, species, and health status of animals. Wheat middlings or “midds” are a by-product of flour milling and are used in a wide range of livestock rations including frequent inclusion in pelleted feeds. The objectives of the current study were to determine the occurrence of mycotoxins in wheat midds samples and to evaluate the potential risk posed to livestock. Since November 2015, 97 samples submitted from 21 states and provinces have been screened via LC-MS/MS technique for the presence of six major mycotoxin groups: aflatoxins, type A trichothecenes, type B trichothecenes (B-Trich), fumonisins, zearalenone, and ochratoxin A (OTA) at Romer Labs (Union, MO, USA) or Activation Laboratories (Ancaster, Ontario, Canada). A subset of samples were also screened for the presence of six ergot alkaloids. Parameters of the main mycotoxins detected are presented in Table 1. On average, 1.7 mycotoxin groups were detected per sample with 91.8% of samples testing positive for at least one mycotoxin. The B-Trich deoxynivalenol was detected in 89.7% of samples (mean 1871.5 ± 157.5 ppb). OTA was also frequently detected (30.9% positive), but at low risk levels (4.2 ± 0.5 ppb). Out of 33 samples screened for ergot alkaloids, 72.7% were positive (493.3 ppb ± 68.3 ppb). Wheat midds are a commonly used feed ingredient for various livestock species. The types and concentrations of mycotoxins detected may pose challenges to livestock health, performance, and reproduction. Special consideration for young animals which are especially susceptible to mycotoxin challenges, such as calves consuming starter feeds, is warranted.

170 Trends in mycotoxin contamination in the united states corn

Abstract Mycotoxins are harmful secondary fungal metabolites and are of key concern to food and feed safety globally. In addition to compromised performance, mycotoxins negatively impact animal health. Although classic signs such as decreased feed intake and vomiting are known in the field as indicators for exposure, mycotoxins act as predisposing factors for diseases by immune suppression, causing inflammation, and modulating the gastrointestinal environment, even at low levels. This survey presents mycotoxin levels of corn samples from the 2018 harvest and compares these levels with those in previous years. New crop corn samples from various sources, were submitted starting from mid-August 2018, and consisted of corn (70%), corn silage (18%), and corn byproduct (12%). Samples were analyzed utilizing the liquid chromatography and tandem mass spectrometry (LC-MS/MS) method for six major mycotoxin groups: aflatoxins (Afla), type A trichothecenes (A-Trich), type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN), and ochratoxin-A (OTA). Data are presented for major mycotoxin classes in Table 1. The majority of samples contained at least 1 detectable mycotoxin with co-occurrence (≥ 2 mycotoxins) similar to 2017, and less than 2016. Prevalence of B-Trich has decreased compared with previous years, but average ppb is similar to 2017. Prevalence and average ppb of ZEN are similar to 2017, while FUM has increased in both prevalence and average ppb. Alfa prevalence has increased and average ppb is numerically higher than the previous two years. The preliminary results from the 2018 corn harvest suggest a continued risk from mycotoxins produced by Fusarium fungal species, and a potential increased risk of Afla compared to previous years. Because of the risk of multi-mycotoxin contamination in corn samples thus far, multiple mitigation strategies are needed beyond just adsorption, including biotransformation support of the immune system and liver function.

PSXIV-31 Mycotoxin Occurrence in the 2017 US Corn Crop.

Mycotoxins are harmful secondary fungal metabolites which contaminate a wide range of feedstuffs. Consumption of these toxic substances, even at low levels, can negatively impact animal health and productivity. This survey presents information regarding mycotoxin contamination of samples from the 2017 corn harvest compared to the prior two harvest years. A total of 596 new crop corn samples (grain, fermented feeds, and by-products) were submitted from mid-August 2017 to March 2018 and analyzed via LC-MS/MS technique for the presence of six major mycotoxin groups: aflatoxins, type A trichothecenes, type B trichothecenes (B-Trich), fumonisins (FUM), zearalenone (ZEN) and ochratoxin A. Fusariummycotoxin contamination parameters were compared year-to-year using the Kruskal-Wallis Test (Prism 7, GraphPad Software, La Jolla, CA) and are presented in Table 1. Prevalence of ZEN and FUM are less in 2017 compared to 2016, while B-Trich prevalence are similar among years. Co-occurrence of mycotoxins in the 2017 crop has decreased from 2016, but is numerically higher than 2015. Although mean DON concentration has decreased versus 2016, levels are numerically greater compared to those from the 2015 harvest. FUM prevalence has significantly decreased from the 2016 crop, but was comparable to 2015 corn. Despite the similarity in prevalence, mean FUM contamination levels are significantly greater this year than what was observed in 2015. Additionally, ZEN prevalence was down versus 2016, but significantly greater than 2015. The preliminary results of the 2017 corn harvest survey suggest a continued risk from Fusarium mycotoxins. The potential for multi-mycotoxin contamination validates use of multiple mitigation strategies to properly address animal health and performance concerns.

Molecular Verification of Bloom-forming Aphanizomenon flos-aquae and Their Secondary Metabolites in the Nakdong River.

Aphanizomenon spp. have formed harmful cyanobacterial blooms in the Nakdong River during spring, autumn, and now in winter, and the expansion of blooming period and area, associated with the global warming is predicted. The genus Aphanizomenon has been described to produce harmful secondary metabolites such as off-flavors and cyanotoxins. Therefore, the production of harmful secondary metabolites from the Aphanizomenon blooms in the Nakdong River needs to be monitored to minimize the risk to both water quality and public health. Here, we sampled the cyanobacterial blooms in the Nakdong River and isolated ten Aphanizomenon strains, morphologically classified as Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault 1888. Phylogenetic analysis using 16S rRNA and internal transcribed spacer (ITS) region nucleotide sequences confirmed this classification. We further verified the harmful secondary metabolites-producing potential of A. flos-aquae isolates and water samples containing cyanobacterial blooms using PCR with specific primer sets for genes involved in biosynthesis of off-flavor metabolites (geosmin) and toxins (microcystins, saxitoxins and cylindrospermopsins). It was confirmed that these metabolite biosynthesis genes were not identified in all isolates and water samples containing only Aphanizomenon spp. Thus, it is likely that there is a low potential for the production of off-flavor metabolites and cyanotoxins in Aphanizomenon blooms in the Nakdong River.

Cyanobacteria blooms induce embryonic heart failure in an endangered fish species

Cyanobacterial blooms drive water-quality and aquatic-ecosystem deterioration in eutrophic lakes worldwide, mainly owing to their harmful, secondary metabolites. The response of fish exposed to these cyanobacterial chemicals, however, remains largely unknown. In this paper, we employed an endangered fish species (Sinocyclocheilus grahami) in Dianchi Lake, China to evaluate the risks of cell-free exudates (MaE) produced by a dominant cyanobacterium (Microcystis aeruginosa) on embryo development, as well as the molecular mechanisms responsible. MaE (3d cultured) caused a reduction of fertilization (35.4%) and hatching (15.5%) rates, and increased mortality rates (≤90.0%) and malformation rate (27.6%), typically accompanied by heart failure. Proteomics analysis revealed that two greatest changed proteins – protein S100A1 (over-expressed 26 times compared with control) and myosin light chain (under-expressed 25 fold) – are closely associated with heart function. Further study revealed that heart failure was due to calcium ion imbalance and malformed cardiac structure. We conclude that harmful secondary metabolites from cyanobacteria may adversely affect embryo development in this endangered fish, and possibly contribute to its disappearance and unsuccessful recovery in Dianchi Lake. Hazardous consequences of substances released by cyanobacteria should raise concerns for managers addressing recovery of this and other imperiled species in affected lakes.