• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.47-52
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• 1998

A rice cultivar (Japonica type), Cheong-cheong, was used to examine the ability as a substrate for aflatoxin production. Brown rice samples were inoculated with Aspergillus parasiticus, stored at various conditions, and observed the production of aflatoxin $B_1$ during storage. Enzyme-linked immunosorbent assay (ELISA) was performed to detect aflatoxin $B_1$ in the samples. A temperature of $28^{\circ}C$ favored the aflatoxin production in the samples. Remoisturizing brown rice to 15.8% encouraged the fungus to produce the aflatoxin significantly (p$B_1$ production in rice, and also indicated that other factors such as husking and storage periods were also risk determinants. This study provided evidence that rice could be an efficient medium for aflatoxin production.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.428-432
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• 1999

This study was performed to investigate the possible effect of sunlight on the reduction or degradation of mycelia and aflatoxins. The mycelia and aflatoxins were produced by Aspergillus parasiticus ATCC 15517 in a yeast-extract sucrose broth (YES) and potato-dextrose agar (PDA) and then exposed to sunlight. The weight of mycelia was decreased to 76.8% in 8 hours and to 66.7% in 168 hours(p<0.05). The total aflatoxin level was significantly decreased to below 50% (46.3% in the YES broth and 49.6% in the PDA) in 8 hours (p<0.05). After 168 hours, a 90.4％ degradation of aflatoxin in the YES broth and a 77.2% degradation of aflatoxin in the PDA was observed, respectively (p<0.01). The results showed that the degradation ratios of total aflatoxin level increased with increased exposure time to sunlight. These results indicate that sunlight could be an effective factor in aflatoxin degradation although its effect on mycelia was less pronounced.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.759-766
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• 1997

From Nuruks, a traditional Korean starter for rice wine, collected from 42 different areas in Korea, 111 fungal strains were isolated. These isolates were identified as 25 species belonging to seven genera of Rhizopus oryzae(14 strains), R. oligosporus(8 strains), R. nigricans(5 strains), R. arrhizus (5 strains), Aspergillus oryzae(12 strains),Asp. parasiticus(8 strains), Asp. fumigatus(3 strains), Asp. ochraceus(7 strains), Asp. wentii(5 strains), Asp. parasiticus(8 strains), Asp. penicilloides(3 strains), Asp. clavatus(4 strains), Penicillium purpurogenum(2 strains), Pen. glabrum(1 strain), Pen. granulaturm (1 strsin), Pen. fellutanum(1 strain), Geotrichum candidum(2 strains), Absidia corymbifera(12 strains), Mucor racemosus(2 strains), M. plumbeus(2 strains) and Curvularia lunatus(3 strains).

• Korean Journal of Food Science and Technology
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• v.14 no.2
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• pp.162-167
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• 1982

The influence of temperature and moisture on aflatoxin production on solid substrate(barley) by Aspergillus parasiticus NRRL 2999 has been studied in some detail. The optimum temperature for production of aflatoxin under the conditions employed is 25 and $30^{\circ}C$. No aflatoxin was detected at the moisture levels of 13%, and only traces at 16% moisture. The ratio of the production of aflatoxin B to G varied with temperature and moisture level. Aflatoxin G is elabolated at a more rapid rate than B and also metabolized at a more rapid rate. Also lower temperatures favored the production of aflatoxin G. The intensity of the yellow pigment of the chloroform extracts correlated with the concentration of aflatoxin.

• The Korean Journal of Mycology
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• v.9 no.1
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• pp.1-6
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• 1981

The effect of gamma irradiation on production and accumulation of aflatoxin on natural substrate (barley) by Aspergillus parasiticus NRRL 2999 has been studied in some detail. Gamma irradiation at five doses, 0, 50, 100, 200 and 400 Krad was applied to the grain either soon after moisture equilibration (3 days after inoculation) or 10 days later (13 days after inoculation). And the results were as in the followings. 1. Increase in moisture content from 17% to 25% greatly increased the aflatoxin concentration, especially at zero irradiation dose. 2. Prolongation of the incubation period prior to irradiation from 3 to 13 days resulted in greater accumulation of aflatoxin. 3. Two hundreds Krad applied 13 days after inoculation on barley stored at 25% moisture (100% RH) and $25^{\circ}C$ led to higher aflatoxin production than 100 Krad or even 50 Krad. 4. The relative proportion of the principal aflatoxins in relation to irradiation showed that aflatoxin G was elaborated at a significantly higher rate than aflatoxin B.

• Korean Journal of Microbiology
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• v.24 no.4
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• pp.352-356
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• 1986

A study was carried out to determine the effect of ginseng saponin an its related materials on aflatoxin production by Aspergillus parasiticus NRRL2999 in glucose-salts(GS) medium. Maximal growth of the mold and AF froduction in the medium occurred after 5 and 9 days at $28^{\circ}C$, respectively. When various concentrations of saponin added to the medium aflatoxin synthesis were significantly reduced (p<0.05) compared to the control after 9 days at $28^{\circ}C$. 0.05% of saponin inhibited aflatoxin production most effectively in the low concerntrations of saponin (0.01-0.2%) and the toxin synthesis reduced with an increasing concentrations of saponin in the high concentrations (0.03-5.0%). Various concentrations (0.01-1.0%) of saponin diol and triol in the media also caused to reduce aflatoxin synthesis by the mold (p<0.05). All saponin fractions were found to decrease aflatoxin production significantly. Saponin fraction numbers of 1,2,4 and 6 were shown to reduce aflatoxin production effectively, and the number 1 was the most effective. Addition of 0.05% of nucleic acid related materials to the medium reduced aflatoxin production (p<0.05). Aflatoxins could not be found in broth at all, but in mycelia when 0.05% of caffeine was added to the medium. Aflatoxin synthesis was well correlated with total lipid synthesis, growth and glucose uptake. When aflatoxin synthesis inhibited (5.0% of saponin) both total lipid synthesis and growth were stimulated and the efficiency of glucose utilization was reduced.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.117-126
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• 1984

Aflatoxins are toxic and carcinogenic secondary metabolites which are produced by trains of A. flavus and A. parasiticus during their growth on foods and feedstuffs. Aflatoxins are a group of closely related heterocyclic compounds of which $B_1$, $B_2$, and $G_2$ are the major members. Aflatoxins are synthesized via a polyketide pathway in which the general steps are acetate, an-thraquinones, xanthone and aflatoxins. Aflatoxin formation is favored by high moisture or high $a_w$(0.95${\sim}$0.99). The limiting $a_w$ for aflatoxin production on agricultural commodities is 0.83. Optimum temperature for aflatoxin production by the molds is $25{\sim}30^{\circ}C$ and the incubation time for the maximum production of the toxin is 7${\sim}$15 days. The limiting temperatures for aflatoxin production are ${\leq}7.5^{\circ}C\;and\;\geq40^{\circ}C$. Cycling temperatures may or may not stimulate aflatoxin production depending on the amplitude of cycling, substrate and strains of molds. Aflatoxin pro-ducing molds are aerobic organisms and thus have a requirement for oxygen. A decreasing $O_2$ concentration and/or increasing concentrations of $CO_2$ or $N_2$ depress the mold growth and aflatoxin formation. A. flavus grows competitively or associatively in the presence of other microorganisms and occasionally loses the competition with other microorganisms. Some lactic acid bacteria have been shown to reduce growth and aflatoxin production by A. parasiticus. Carbon source is the most important nutritional factors affecting aflatoxin formation by the molds. Sucrose, fructose and glucose are the most favorable carbon sources. Food substrates of plant derived products which have high carbohydrate content such as agricultural commodities and their products are most vulnerable to contamination by aflatoxins.

• Journal of Food Hygiene and Safety
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• v.7 no.1
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• pp.15-22
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• 1992

This study was conducted to determine the potential of grapefruit seed extract to support Aspergillus parasilicus growth and aflatoxin production. The grapefruit seed extract inhibited the growth and aflatoxin production of the fungi in the level of more than 4,000 ppm and 3,000 ppm in the medium, respectively. Grapefruit seed extract appears to block the conversion of acetate, averufin and versiconal acetate into aflatoxin in vitro experiments. The addition of grapefruit seed extract to the feeding experiment systems did not inhibit the incorporation of 14C-labeled versicolorin A, versicolorin A hemiacetal and sterigmatocystin into aflatoxin. In the electron microscopic examination the biocidal action of grapefruit seed extract was related to the disturbance of cell menbrane funtion, inhibiting cellular respiration.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.259-264
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• 1985

The research was carried out for the purpose of finding effects of gerbal saponins on aflatoxin synthesis by Aspergillus parasitics NRRL 2999. A. parasiticus with $10^6$ conidia were grown at $30^{\circ}C$ for 9 days on the enriched medium that is optimum for the frowth and aflatoxins production by the mold. The inhibitory effect on the growth and aflatoxins produced by the mold occurred in the presence of 0.36% of crude red-ginseng saponin showing both the growth and aflatoxins production come to 62.3% (growth), 38.7% (aflatoxin $B_1$) and 22.9% (aflatoxin $G_1$) of the control. Thd next effective saponin to inhibit the growth and aflatoxins production was from burdock seeds. However, saponin extracted from honeysuckle flowers had no inhibitory effect. The mold caused no changes in the pH of the medium when it contained red-ginseng saponin. Red-ginseng saponin was more effective than the white-ginseng in inhibiting both the growth and aflatoxin production.

• Archives of Pharmacal Research
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• v.11 no.2
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• pp.139-144
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• 1988

Examination of many microorganisms and soil isolated for the activity of aspartase proved that R, rubra, G, suboxydans, A. versicolor, P. purpurogenum, E. coli, Ps. aeruginosa, A. gigantus, A, unguis, A. parasiticus and a soil isolate (S-90) had high activity of aspartase. Comparison of the activity of the aspartase by cell free extracts of these microorganisms with the activity of the enzyme catalyzing the deamination of aspartame by the same cell free extracts showed similar kinetic characteristics. The aspartase existing in the cell free extracts seemed to catalyze the deamination of aspartame, too.