• Food Science and Preservation
• /
• v.30 no.1
• /
• pp.28-41
• /
• 2023

Non-aflatoxigenic Aspergillus oryzae and aflatoxigenic A. flavus cannot be clearly identified by partial sequencing of the internal transcribed spacer (ITS) and 18S ribosomal ribonucleic acid (18S rRNA) regions. This study aimed to compare the accuracy among three aflatoxin detection methods using ultra-performance liquid chromatography (UPLC), high-performance liquid chromatography (HPLC), and an enzyme-linked immunosorbent assay (ELISA) kit and to select the non-aflatoxigenic Aspergillus sp. isolated from soybean paste. All analytical methods were suitable according to the international standards of Codex Alimentarius FAO-WHO (CODEX) or the Ministry of Food and Drug Safety (MFDS). UPLC exhibited the best of limit of detection (LOD) and limit of quantification (LOQ). Based on UPLC, HPLC, and the ELISA kit assay, the P5 and P7 strains isolated from soybean paste had 1,663.49, 1,468.12, and >20 ㎍/kg and 1,470.08, 1,056.73, and >20 ㎍/kg, respectively, detected and re-identified as A. flavus. In contrast, the P3 and P4 strains (A. oryzae), which were detected below the MFDS standards in all assays, were confirmed as non-aflatoxigenic fungi. Among the methods evaluated for quantitative analysis of aflatoxin, UPLC and HPLC are superior in terms of accuracy, and the ELISA kit rapidly detects low concentrations of aflatoxin. Furthermore, this study demonstrates that any Aspergillus sp. isolated for use as a fermentation starter should be analyzed for potential aflatoxin production using UPLC and HPLC for accurate quantitative analysis or ELISA for the rapid detection of low-level concentrations of aflatoxin.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.7
• /
• pp.1015-1019
• /
• 2003

A 50 day feeding trial was conducted with White Leghorn (WL) laying hens, 42 weeks old, to determine if feeding of varying levels of aflatoxin (AF), ochratoxin A (OA) or their combinations has any effect on their performance and egg quality parameters. Feeding of $T_4$, $T_7$, $T_8$, $T_9$ and $T_10$ caused significant reduction in feed intake of hens. Hen day egg productions were significantly reduced at all the levels of toxins except 0.5 ppm of AF. Maximum reduction in egg production was noticed at 2 and 4 ppm of AF and OA, respectively. Average body weight and egg weight were not affected by toxin feeding. The feed efficiency in terms of net feed efficiency and feed consumed per dozen egg produced was significantly reduced at higher levels of both the toxins and their combinations. Feed consumption for production of 1 kg egg mass remained uninfluenced due to aflatoxin feeding whereas significant increase in the value of the same was noticed at 4 ppm level of OA and combination of 1 and 2 ppm of AF and 2 and 4 ppm of OA ($T_9$ and $T_10$), respectively. Various levels of OA (1-4 ppm) and all the combination of two toxins ($T_8$, $T_9$ and $T_10$) significantly altered the shape index of eggs in laying hens. The shell thickness was significantly reduced by higher level of AF (2 ppm), OA (2 and 4 ppm) and their combination. Albumen index, Haugh Unit and yolk index remained unchanged due to incorporation of toxins in the diet. It is concluded that AF, OA either singly or in combination at higher levels could depress the performance in terms of egg production and feed efficiency significantly. The egg quality parameters i.e. shape index and shell thickness were also significantly affected.

• Journal of Food Hygiene and Safety
• /
• v.12 no.2
• /
• pp.97-101
• /
• 1997

Effect of allylisothiocyanate on the enzyme activites including malate degydrogenase, isocitrate dehydrogenase, NADPH and acetyl CoA which were related to aflatoxin production of Aspergillus parasticus R-716 were invetigated. The activities of malate dehydrogenase (EC.1.1.1.37), isocitrate dehydrogenase (E.C.1.1.1.42) and NADPH oxidase (E.C.1.6.99.1) indicated relatively high in the 50 ppm allylisothiocyanate-added-culture. In contrast, the activity of acetyl CoA in the 50 ppm allylisothiocyanate-added-culture showed rather lower level through the cultivation.

• Mycobiology
• /
• v.46 no.3
• /
• pp.287-295
• /
• 2018

In this study, we evaluated the effect of different temperatures (10, 20, 30, and $40^{\circ}C$) and relative humidities (RHs; 12, 44, 76, and 98%) on populations of predominant grain fungi (Aspergillus candidus, Aspergillus flavus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum) and the biocontrol activity of Pseudomonas protegens AS15 against aflatoxigenic A. flavus KCCM 60330 in stored rice. Populations of all the tested fungi in inoculated rice grains were significantly enhanced by both increased temperature and RH. Multiple linear regression analysis revealed that one unit increase of temperature resulted in greater effects than that of RH on fungal populations. When rice grains were treated with P. protegens AS15 prior to inoculation with A. flavus KCCM 60330, fungal populations and aflatoxin production in the inoculated grains were significantly reduced compared with the grains untreated with strain AS15 regardless of temperature and RH (except 12% RH for fungal population). In addition, bacterial populations in grains were significantly enhanced with increasing temperature and RH, regardless of bacterial treatment. Higher bacterial populations were detected in biocontrol strain-treated grains than in untreated control grains. To our knowledge, this is the first report showing consistent biocontrol activity of P. protegens against A. flavus population and aflatoxin production in stored rice grains under various environmental conditions of temperature and RH.

• Mycobiology
• /
• v.35 no.2
• /
• pp.76-81
• /
• 2007

Lactobacillus casei KC-324 was tested for its ability to inhibit aflatoxin production and mycelial growth of Aspergillus flavus ATCC 15517 in liquid culture. flatoxin $B_{1}$ biosynthesis and mycelial growth were inhibited in both simultaneous culture and individual antagonism assays, suggesting that the inhibitory activity was due to extracellular metabolites. produced in cell-free supernatant fluids of the cultured broth of L. casei KC-324. In cell-free supernatant fluids of all media tested, deMan, Rogosa and Sharpe broth, potato dextrose broth, and Czapek-Dox broth+1% yeast extract showed higher antiaflatoxigenic activity. In these case, fungal growths, however, was not affected as measured by mycelial dry weight. The antiaflatoxigenic metabolites from L. casei KC-324 were produced over wide range of temperatures between $25^{\circ}C$ and $37^{\circ}C$. However, these metabolites were not thermostable since the inhibitory activity of the supernatant was inactivated within 30 minutes at $100^{\circ}C$ and $121^{\circ}C$. The inhibitory activity was not influenced by changing pH of supernatant between 4 and 10. However, the antiaflatoxigenic activity was slightly reduced at pH 10.

• Journal of Food Hygiene and Safety
• /
• v.35 no.5
• /
• pp.438-446
• /
• 2020

Meju and nuruk (respectively soybean and malt) are traditional Korean fermentation starters that are vulnerable to contamination by harmful microorganisms such as aflatoxigenic fungi and their associated aflatoxins (AFs). In this study, Aspergillus spp. were isolated and identified from a total of 57 meju and 18 nuruk samples collected from Korean markets. Their potential aflatoxigenicity was investigated by examining the presence of three aflatoxin biosynthetic genes (aflO, aflP, and aflR) using multiplex polymerase chain reaction (mPCR) assays. Thereafter, aflatoxin production of isolates and the natural occurrence of AFs in meju and nuruk samples were analyzed by high-performance liquid chromatography (HPLC). A total of 177 Aspergillus isolates were identified and 130 isolates were obtained from meju samples. Of these, 25 isolates (19.2%) contained all three aflatoxin biosynthetic genes, and five (20%) of these isolates produced aflatoxins. Forty-seven of the Aspergillus isolates were obtained from nuruk samples, five of which (10.6%) expressed all three AF biosynthetic genes; however, none of these strains produced AFs. HPLC analysis showed that 88% (51/58) of the meju samples and 39% (7/18) of nuruk samples were not contaminated with AFs (below limit of detection). Among the isolates isolated from meju and nuruk, there were aflatoxigenic strains containing all three aflatoxin biosynthetic genes or producing aflatoxin in medium, but the frequency of aflatoxin contamination was low in the meju and nuruk samples.

• Korean Journal of Poultry Science
• /
• v.21 no.2
• /
• pp.113-117
• /
• 1994

Of the 200, 000 known species of molds, only 50 or 60 are known to be harmful to humans or livestock. Certain fungi that grow on grains and grasses can produce chemical substances called mycotoxins that adversely affect performance in poultry. There are several methods of preserving feed ingredients. The list includes: drying, antioxidants, mold inhibitors, organic acids, phosphates, cooking or toasting, fat extraction, blending and fermenting. Mold inhibitors are manufactured to inhibit mold growth and prevent the production of toxic substances. They are fungistats and not fungicides, that is, they only stop the growth of molds. Practical and cost-effective methods to detoxify mycotoxin containing feedstuffs are in great demand. 0.5% hydrated sodium calcium aluminosilicate added to the diet protected chicks from the deleterious effects of aflatoxin-contaminated feed. The dietary addition of antioxidants and methionine also significantly diminished the negative effects on body weight in chicks toxicated with 3.0 ppm aflatoxin B1.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.4
• /
• pp.679-682
• /
• 2002

The alkaloids, piperlongumine, piperine, pipernonaline, and piperoctadecalidine, isolated from Piper longum L., were found to inhibit the biosynthesis of aflatoxin $B_1$ (AF$B_1$) in Aspergillus flavus WRRC 3-90-42-12. Piperlongumine was the most active among the compounds tested, with a 96% inhibition of AF$B_1$biosynthesis at 0.2% (w/v) supplement in a potato dextrose agar (PDA) medium. The three other piperidine alkaloids, pipeline, pipernonaline, and piperoctadecalidine, also inhibited the biosynthesis of AF$B_1$. Of these three alkaloids, piperoctadecalidine exhibited a potent inhibitory activity with a 100% inhibition of AF$B_1$ production at 0.7% (w/v) supplement in a PDA medium. Therefore, piperlongumine and piperoctadecalidine could be used as antiaflatoxigenic agents in agricultural industries. To determine the antiaflatoxigenic mode of action of piperlongumine, further studies are needed.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.11
• /
• pp.1686-1689
• /
• 2003

The ability of ten probiotic bacteria to bind a common food carcinogen aflatoxin $G_1$,$G_2$ and $B_2$ was assessed. The strains were incubated in vitro with aflatoxins and the toxin residues in the supernatant were measured using high performance liquid chromatography. The aflatoxin $G_1$ binding capacity of the strains was found to strain dependent, most efficient binding of AF$G_1$ was observed by L. acidophilus CU028 and L. brevis CU06 which bound approximately 50%. L. acidophilus CU028 was capable of bind approximately 67% of AF$G_2$, difference in their binding ability showed statistical significance (p>0.05). L. acidophilus CU028 and L. helveticus CU 631 were the best binders and the strains were observed to possess variable AF$B_2$-binding ability in the range was from 38.0% to 55.9%. Lactobacillus acidophilus CU028 was the best common binders of the three types of food carcinogen aflatoxins. The application of binding phenomenon in the removal of mycotoxins from contaminated feeds is urgently needed to improve the safety of feeds.

• Mycobiology
• /
• v.50 no.6
• /
• pp.408-419
• /
• 2022

Filamentous fungi that could be classified into Aspergillus flavus/oryzae were isolated from traditionally fermented meju commercially available in Korea. The samples were analyzed for aflatoxin B1 and ochratoxin A contamination by HPLC; however, no toxin was detected. In addition, fungal and bacterial metagenomic sequencing were performed to analyze the microbial distribution in the samples. The results revealed that the distribution and abundance of fungi and bacteria differed considerably depending on the production regions and fermentation conditions of the meju samples. Through morphological analysis, ITS region sequencing, and assessment of the aflatoxin-producing ability, a total of 32 A. flavus/oryzae strains were identified. PCR analysis of six regions with a high mutation frequency in the aflatoxin gene cluster (AGC) revealed a total of six types of AGC breaking point patterns. The A. flavus/oryzae strains did not exhibit the high amylase activity detected in the commercial yellow koji strain (starter mold). However, their peptidase and lipase activities were generally higher than that of the koji isolates. We verified the safety of the traditionally fermented meju samples by analyzing the AGC breaking point pattern and the enzyme activities of A. flavus/oryzae strains isolated from the samples. The isolated strains could possibly be used as starter molds for soybean fermentation.