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Blasticidin S (BcS) is a protein synthesis inhibitor which shows strong growth inhibitory activity against a number of microorganisms. However, BcS inhibited aflatoxin production by Aspergillus flavus without affecting its growth. In order to obtain information about the structure-activity relationship of BcS as an aflatoxin production inhibitor, BcS derivatives were prepared and their aflatoxin production inhibitory activities were evaluated. Among five derivatives, blasticidin S carboxymethyl ester, deaminohydroxyblasticidin S, and pyrimidinoblasticidin S showed inhibitory activity, while the others did not. The IC50 value for aflatoxin production of the carboxymethyl ester derivative was one-fifth of that of BcS although their antimicrobial activities were almost the same. These results indicate that the inhibitory activity of BcS against aflatoxin production was enhanced by esterification of its carboxyl group and that the carboxymethyl ester derivative might be more suitable for practical use than BcS because of the specificity of the carboxymethyl ester derivative, which inhibited aflatoxin production more than BcS. [ABSTRACT FROM AUTHOR]

Commercially available rice grains in Thailand were examined to isolate the monoverticillate Penicillium species responsible for toxic yellowed rice. Penicillium species were obtained from seven out of 10 rice samples tested. Among them, one Penicillium citreonigrum isolate and six Penicillium brocae isolates were morphologically identified. The P. citreonigrum isolate produced the mycotoxin citreoviridin on a yeast extract sucrose broth medium. Mycotoxin surveys showed that citreoviridin was not detected in any samples, but one out of 10 rice samples tested was positive for aflatoxin B1 at a level of 5.9 μg/kg. An Ames test revealed that methanol extracts from rice grains inoculated with selected P. brocae isolates were positive for strains TA100 and YG7108 of Salmonella typhimurium, suggesting the presence of base-pair substitution and DNA alkylation mutagens. Our data obtained here demonstrated that aflatoxin B1 and toxic P. citreonigrum were present on domestic rice grains in Thailand, although limited samples were tested. Penicillium brocae, which may produce mutagenic metabolites, was isolated for the first time from the surface of Thai rice grains. [ABSTRACT FROM AUTHOR]

Macrophages induce the innate immunity by recognizing pathogens through Toll-like receptors (TLRs), which sense pathogen-associated molecular patterns. Myeloid differentiation factor 88 (MyD88), which is an essential adaptor molecule for most TLRs, mediates the induction of inflammatory cytokines through nuclear factor κB (NF-κB). Trichothecene mycotoxin deoxynivalenol (DON) shows immunotoxic effects by interrupting inflammatory mediators produced by activated macrophages. The present study investigates the effect of DON on NF-κB in activated macrophages through MyD88-dependent pathways. DON inhibited NF-κB-dependent reporter activity induced by MyD88-dependent TLR agonists. In addition, lipopolysaccharide-induced phosphorylation of interleukin-1 receptor-associated kinase 1 and inhibitor κBα were attenuated by DON. Furthermore, DON downregulated the expression level of MyD88. These results suggest that DON inhibits NF-κB activation in macrophages stimulated with TLR ligands via MyD88-dependent TLR signals. Therefore exposure to DON may lead to the inhibition of MyD88-dependent pathway of TLR signaling. [ABSTRACT FROM AUTHOR]

There is a strain of Clostridium perfringens, W5052, which does not produce a known enterotoxin. We herein report that the strain W5052 expressed a homologue of the iotalike toxin components sa and sb of C. spiroforme, named Clostridium perfringens iotalike enterotoxin, CPILE-a and CPILE-b, respectively, based on the results of a genome sequencing analysis and a systematic protein screening. In the nicotinamide glyco-hydrolase (NADase) assay the hydrolysis activity was dose-dependently increased by the concentration of rCPILE-a, as judged by the mass spectrometry analysis. In addition, the actin monomer of the lysates of Vero and L929 cells were radiolabeled in the presence of [32P]NAD and rCPILE-a. These findings indicated that CPILE-a possesses ADP-ribosylation activity. The culture supernatant of W5052 facilitated the rounding and killing of Vero and L929 cells, but the rCPILE-a or a non-proteolyzed rCPILE-b did not. However, a trypsintreated rCPILE-b did. Moreover, a mixture of rCPILE-a and the trypsin-treated rCPILE-b enhanced the cell rounding and killing activities, compared with that induced by the trypsintreated rCPILE-b alone. The injection of the mixture of rCPILE-a and the trypsin-treated rCPILE-b into an ileum loop of rabbits evoked the swelling of the loop and accumulation of the fluid dose-dependently, suggesting that CPILE possesses enterotoxic activity. The evidence presented in this communication will facilitate the epidemiological, etiological, and toxicological studies of C. perfringens food poisoning, and also stimulate studies on the transfer of the toxins' gene(s) among the Genus Clostridium. [ABSTRACT FROM AUTHOR]

A survey of the contamination of wheat, barley, and Japanese retail food by four Fusarium mycotoxins, deoxynivalenol (DON), zearalenone (ZEN), T-2 toxin (T-2), and HT-2 toxin (HT-2), was performed between 2010 and 2012. A method for the simultaneous determination of the four mycotoxins by liquid chromatography-tandem mass spectrometry was validated by a small-scale interlaboratory study using two spiked wheat samples (DON was spiked at 20 and 100 μg/kg and ZEN, T-2, and HT-2 at 6 and 20 μg/ kg in the respective samples). The recovery of the four mycotoxins ranged from 77.3 to 107.2%. A total of 557 samples of 10 different commodities were analyzed over 3 years by this validated method. Both T-2 and HT-2 were detected in wheat, wheat flour, barley, Job's tears products, beer, com grits, azuki beans, soybeans, and rice with mixed grains. Only T-2 toxin was detected in sesame seeds. The highest concentrations of T-2 toxin (48.4 μg/kg) and HT-2 toxin (85.0 μg/kg) were present in azuki beans and wheat, respectively. DON was frequently detected in wheat, wheat flour, beer, and com grits. The contamination level of wheat was below the provisional standard in Japan (1,100 μg/kg). The maximum contamination level of DON was present in a sample of a Job's tears product (1,093 μg/kg). ZEN was frequently detected in Job's tears products, corn grits, azuki beans, rice with mixed grains, and sesame seeds. A sample of a Job's tears product presented the highest ZEN contamination (153 μg/kg). These results indicate that continuous monitoring by multiple laboratories is effective and necessary due to the percentage of positive samples detected. [ABSTRACT FROM AUTHOR]

Food poisoning has been reported after the consumption of raw horsemeat in Japan. Diarrhea with a short incubation period is a common symptom in such cases of food poisoning. Cysts found in horsemeat ingested by patients have been identified as Sarcocystis fayeri based on morphological and genetic evaluation and findings from experimental feeding of cysts to dogs, which resulted in the excretion of sporocysts. The extracts of the horsemeat containing the cysts produced a positive enterotoxic response in the rabbit ileal loop test. Intravenous injection of a 15-kDa protein isolated from the cysts induced diarrhea and lethal toxicity in rabbits, and the protein produced enterotoxicity in the ileal loop test as did the extracts of the horsemeat containing the cysts. The partial amino acid sequence of the 15-kDa protein was homologous to the actin-depolymerizing factor of Toxoplasma gondii and Eimeria tenella. These findings indicate that the 15-kDa protein of S. fayeri is a toxin that causes food poisoning after consumption of parasitized horsemeat. [ABSTRACT FROM AUTHOR]

Nivalenol (NIV) is a trichothecene mycotoxin produced by Fusarium fungi that frequently contaminates agricultural commodities. Dietary administration of NIV to adult mice affects the renal glomeruli, but data about NIV toxicity in human infants are limited. To evaluate the effects of NIV on infant kidneys, 3-week-old male ICR-derived glomerulonephritis (ICGN) and ICR mice were administered 0, 4, 8 or 16 ppm NIV in diet for 4 weeks, and their renal status was compared with age-matched or adult ICR mice. In ICGN mice, the number of glomeruli showing mesangial expansion and a-smooth muscle actin (SMA)-positive mesangial cells was higher with 16 ppm NIV compared with controls. No other significant differences were observed in ICGN mice. In infant ICR mice, the IgA serum concentrations were significantly elevated without glomerular morphological changes in the 16 ppm NIV group. There was no difference in NIV sensitivity in the kidneys of infant ICGN and ICR mice. These data suggest that the kidneys in infant mice are not sensitive to nivalenol under the present conditions. [ABSTRACT FROM AUTHOR]

To investigate the diversity of stress tolerance levels in Vibrio parahaemolyticus, 200 V. parahaemolyticus strains isolated from various coastal environments, seafood, and human clinical cases were exposed to acid, low-osmolality, freezing-thawing, and heat stresses. Tolerance against acid stress was higher in the virulent (tdh- and/or trh-positive) strains than in the avirulent (tdh- and trh-negative) strains. Tolerance against low-osmolality, freezing-thawing, and heat stresses was higher in the clinical strains of tdh- and/or trh-positive V. parahaemolyticus than in the coastal environment- and seafood-originated strains of tdh-and/or trh-positive V. parahaemolyticus. Tolerance against acid stress was higher in the strains isolated from coastal seawater at ≤15°C than in the strains isolated at ≥20°C. Tolerance against heat stress was higher in the avirulent strains than the virulent strains, and in the strains isolated from coastal seawater at ≥20°C than the strains isolated from coastal seawater at ≤15°C. Therefore, this study demonstrated that the diversity of stress tolerance levels in V. parahaemolyticus strains depended on their source and whether they harbored virulence genes. In particular, there was significantly greater tolerance against acid in the virulence gene-harboring strains and strains isolated from low-temperature seawater. Because the stress tolerances of V. parahaemolyticus have direct influences for the survival in environment and food, it is important for the prevention of foodborne infection to control the stress-tolerant strains. [ABSTRACT FROM AUTHOR]

The present study was performed to elucidate toxicity profile of citrinin (CTN) after repeated oral doses for 90 days, especially on the kidneys and female reproductive organs using female BALB/c mice. We first performed a 70-day repeated oral dose toxicity study of CTN by setting the doses at 1.25 and 7.5 ppm in the drinking water (Experiment 1). As a result, CTN did not produce any toxicity in the kidneys, liver, and female genital organs/tracts, except for a slight increase of relative ovary weight. We, next, performed 90-day repeated oral dose toxicity study of CTN by increasing the dose levels at 15 and 30 ppm in the drinking water. The results suggested that CTN did not produce any toxicity in the kidneys, liver, and female genital organs/tracts, except for increase of both absolute and relative ovary weights accompanying increase of large follicles at ≥ 15 ppm. On the basis of these findings, the lowestobservable- adverse-effect level of CTN was 15 ppm (2.25 mg/kg body weight/day) in the drinking water for female BALB/c mice after 90-day oral treatment. [ABSTRACT FROM AUTHOR]

We developed a purification method based on liquid chromatography--tandem mass spectrometry for the identification of deoxynivalenol (DON), its acetylated derivatives (3-acetyl-deoxynivalenol and 15-acetyl-deoxynivalenol), and a glycosylated derivative (deoxynivalenol-3-glucoside [D3G]) in corn-based products. The analytes were extracted from samples with acetonitrile-water (85:15, vol/vol) and then purified with multifunctional columns. Evaluation of five kinds of multifunctional columns revealed that DON and its acetylated derivatives were recovered well (96 to 120%) by all columns, but D3G was recovered adequately (93.5%) by only one column, InertSep VRA-3. Samples of corn grits and corn flour were analyzed using the purification method with InertSep VRA-3. DON, D3G, and 15-acetyl-deoxynivalenol were the major contaminants in the samples harvested in 2009, but only DON was detected in the samples harvested in 2010. These results suggest that the purification method using InertSep VRA-3 is effective for identification of DON and its derivatives in corn-based products. [ABSTRACT FROM AUTHOR]

A comprehensive and quantitative analysis of the mycoflora on the surface of commercial fruit was performed. Nine kinds of fruits grown in Japan were tested. Overall fungal counts on the fruits ranged from 3.1 to 6.5 log CFU/g. The mean percentages of the total yeast counts were higher than those of molds in samples of apples, Japanese pears, and strawberries, ranging from 58.5 to 67.0%, and were lower than those of molds in samples of the other six fruits, ranging from 9.8 to 48.3%. Cladosporium was the most frequent fungus and was found in samples of all nine types of fruits, followed by Penicillium found in eight types of fruits. The fungi with the highest total counts in samples of the various fruits were Acremonium in cantaloupe melons (47.6% of the total fungal count), Aspergillus in grapes (32.2%), Aureobasidium in apples (21.3%), blueberries (63.6%), and peaches (33.6%), Cladosporium in strawberries (38.4%), Cryptococcus in Japanese pears (37.6%), Penicillium in mandarins (22.3%), and Sporobolomyces in lemons (26.9%). These results demonstrated that the mycoflora on the surfaces of these fruits mainly consists of common pre- and postharvest inhabitants of the plants or in the environment; fungi that produce mycotoxins or cause market diseases were not prominent in the mycoflora of healthy fruits. These findings suggest fruits should be handled carefully with consideration given to fungal contaminants, including nonpathogenic fungi, to control the quality of fruits and processed fruit products. [ABSTRACT FROM AUTHOR]