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PubMed1997

Influence of white light, near-UV irradiation and other environmental conditions on production of aflatoxin B1 by Aspergillus flavus and ochratoxin A by Aspergillus ochraceus.

The effects of illumination, near-ultraviolet, incubation temperature pH and some minor elements on the growth rate and production of aflatoxin B1 by A. flavus and ochratoxin A by A. ochraceus were investigated. Aflatoxin B1 and ochratoxin A production was considerably higher in the light than in the dark. The greatest aflatoxin B1 and ochratoxin A production was occurred after 11 days of fermentation with light- and dark-grown cultures at 25 degrees C. The mycelial dry weight was also greater in the light than in the dark for both A. flavus and A. ochraceus. Exposure of conidia to near-UV irradiation increased mycelial dry weight and mycotoxins by both fungi more than white light. The greatest aflatoxin B1 and ochratoxin A was at 25 degrees C with UV-grown culture (24 h exposure) producing a mean of 400 and 260 micrograms/50 ml of medium, respectively. The maximum aflatoxin B1 and ochratoxin A yield was obtained at pH 5.5 and with increasing the initial pH to near neutrality, both mycotoxins yield decreased. Iron, copper and zinc were observed to stimulate aflatoxin B1 and ochratoxin A production and enhanced the growth rate of both A. flavus and A. ochraceus.

Aflatoxin B1↗

PubMed1977

Effect of aflatoxin B1 on hepatic polyribosomes and protein synthesis in the rat.

This study was concerned with the effect of aflatoxin B1 on protein synthesis in rat liver. Specifically, the effect of the administration of aflatoxin B1 (6.0 mg/kg body weight) on hepatic polyribosomes (free and membranebound), protein synthesis in vitro, and initiation factors activity of rats within 3-12 h was investigated. The results revealed that aflatoxin B1 rapidly led to disaggregation of free and membrane-bound polyribosomes, to inhibition of in vitro protein synthesis by both populations of polyribosomes, to little or no effect on the activities of initiation factors, and to defective ribosomes, particularly the 60S ribosomal subnits, of both types of polyribosomes. Comparative studies on the effects of aflatoxin B1 and actinomycin D revealed progressive disaggregation by both hepatic free and membrane-bound polyribosomes after aflatoxin B1 but not only of the free polyribosomes after actinomycin D.

Aflatoxins↗

PubMed1999

Aflatoxin B1 and fumosin B1 in mixed cultures of Aspergillus flavus and Fusarium proliferatum on maize.

Production of aflatoxin B1 and fumonisin B1 in pure and mixed cultures of Aspergillus flavus and Fusarium proliferatum were determined on irradiated maize seeds inoculated with different spore concentrations at 0.97 water activity (a(w)) and a temperature of 25 degrees C. The highest levels of aflatoxin B1 were produced by A. flavus at the lowest levels of inoculum (10(3) spore ml(-1)). There was no spore concentration influence on fumonisin B1 production after 10, 20 and 35 days of incubation. When A. flavus was co-inoculated with F. proliferatum, aflatoxin B1 production was inhibited. The higher the inocula levels of Fusarium produced, the higher the inhibition and this inhibition increased during the incubation period. Total inhibition was reached at 35 days of incubation. There was no interaction influence on fumonisin B1 production at all inoculum levels assayed. These results suggest that under optimal environmental conditions of substrate, water activity and temperature, the interaction between A. flavus and F proliferatum could produce inhibition of aflatoxin B1 and stimulation of fumonisin B1.

Aflatoxin B1↗

PubMed1999

Co-mutagenicity of coumarin (1,2-benzopyrone) with aflatoxin B1 and human liver S9 in mammalian cells.

Coumarin (1,2-benzopyrone), a natural dietary constituent and drug currently under evaluation for treatment of certain cancers and lymphedema, reduces polycyclic aromatic hydrocarbon-induced neoplasms in rodents. Because most rodents metabolize coumarin through 3,4-epoxidation, whereas 7-hydroxylation predominates in humans, their suitability as a model for coumarin effects in humans has been questioned. We examined coumarin chemoprotection against the promutagen and dietary contaminant aflatoxin B1 with human liver S9 bioactivation in the Chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyltransferase mutation assay. Coumarin in the absence of aflatoxin B1 was not mutagenic or cytotoxic up to 500 microM. When included with either 1 or 10 microM aflatoxin B1, coumarin produced a dose-dependent increase in mutant frequency and cytotoxicity. At concentrations greater than 50 microM, coumarin stimulated human liver S9 bioactivation of aflatoxin B1 to the mutagenic 8,9-epoxide. This increase was 12- and fivefold at 500 microM coumarin with 1 and 10 microM aflatoxin B1, respectively, compared with incubations with aflatoxin B1 alone. These findings differ from previous results with liver S9 from other species, and indicate that coumarin co-mutagenicity with aflatoxin B1 and human liver S9 is through increased aflatoxin B1 bioactivation.

Aflatoxin B1↗

PubMedDate not supplied

Rapid immunochemical screening method for aflatoxin B1 in human and animal urine.

A method has been developed to determine the presence of aflatoxin B1 in the urine of animals (including humans) by utilizing commercial immunochemical kits that can be used in the field. Urine is treated with diatomaceous earth and filtered to clarify the sample; 2-3 ppb aflatoxin B1, corresponding to about 300 ppb in the ingested feed/food, can be detected in the filtered urine without further purification. To improve sensitivity, the urine filtrate is passed through a C18 solid phase column to extract the aflatoxin. The column is washed with acetonitrile-water (15 + 85) and water, aflatoxin B1 is eluted with methanol-water (7 + 3), and water is added to the eluate, which is then tested for aflatoxin with the test kit. The limit of detection is 0.2 ppb, reflecting consumption of 40 ppb or more aflatoxin in the feed/food. When the initial sample volume is adequate, purification through the C18 column step is usually sufficient. For limited sample volumes, the eluate from the C18 column is mixed with water, added to an immunosorbent affinity column, and washed with water to remove excess sample matrix and impurities. Aflatoxin B1 is eluted with acetonitrile. The extract is evaporated under nitrogen and the residue is redissolved in methanol-water (25 + 75). At this purification stage, the limit of detection is reduced to 0.05 ppb.

Aflatoxin B1↗

PubMed2002

Impairment of cell cycle progression by aflatoxin B1 in human cell lines.

Aflatoxin B1 is a mycotoxin produced by Aspergillus flavus and Aspergillus parasiticum, which may be present as a food contaminant. It is known to cause acute toxic effects and act as a carcinogenic agent. The carcinogenic action has been related to its ability to form unstable adducts with DNA, which represent possible mutagenic sites. On the other hand, the primary cellular target responsible for its toxic action has not yet been clearly identified. Previous data suggested a possible correlation between cell proliferation and responsiveness to aflatoxin toxicity. These observations led us to investigate the effect of the toxin on cell cycle progression of three human cell lines (HepG2, SK-N-MC and SK-N-SH derived from liver and nervous tissue tumours); they were shown to display different responses to toxin exposure and have different growth kinetics. We performed analysis of the cell cycle, DNA synthesis and expression of p21 and p53 in the presence and absence of the toxin in all cell lines exposed. The results of cell cycle cytofluorometric analysis show significant alterations of cell cycle progression as a result of toxin treatment. In all cell lines exposure to a 24 h toxin treatment causes a dose-dependent accumulation in S phase, however, the ability to recover from impairment to traverse S phase varies in the cell lines under study. SK-N-MC cells appear more prone to resume DNA synthesis when the toxin is removed, while the other two cell lines maintain a significant inhibition of DNA synthesis, as indicated by cytofluorimetry and [(3)H]dTR incorporation. The level of p53 and p21 expression in the three cell lines was examined by western blot analysis and significant differences were detected. The ready resumption of DNA synthesis displayed by SK-N-MC cells could possibly be related to the absence of p53 control of cell cycle progression.

Aflatoxin B1↗

PubMedDate not supplied

Visual and semiquantitative spectrophotometric ELISA screening method for aflatoxin B1 in corn and peanut products: follow-up collaborative study.

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, The Netherlands, Switzerland, Tunisia, and the United States. Twelve raw and roasted peanut and corn portions containing various concentrations of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on competition between an enzyme-conjugated aflatoxin B1 and (free) aflatoxins in the test sample for aflatoxin-specific antibodies coated onto interior surfaces of microtiter wells. After a wash step to remove all unbound aflatoxins, a substrate added to each well is catalyzed from a colorless to a blue solution by any bound enzyme-conjugated aflatoxin B1 present. The intensity of the color decreases as the amount of free aflatoxin B1 in the test portion increases. Final determination of aflatoxin concentrations can be made by either visual comparison with standard solutions or spectrophotometric comparisons (at 650 nm) to knowns. Overall correlation was good between ELISA and thin-layer chromatographic results for corn and roasted peanut products, with 93 and 98% correct responses for visual and instrumental determinations, respectively. For instrumental determinations of aflatoxin in corn and roasted peanuts in the less than or equal to 20 ng/g range, the relative standard deviations for repeatability (RSDr) were 14.9 and 41.4%, respectively, and the relative standard deviations for reproducibility (RSDR) were 45.7 and 43.5%, respectively. For instrumental determination of greater than 20 ng/g, the respective RSDr and RSDR values were 19.4 and 52.7% for corn and 23.3 and 23.3% for roasted peanuts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin B1↗

PubMed2000

Binding of aflatoxin B1 to bifidobacteria in vitro.

Aflatoxins are mycotoxins that cause health and economic problems when they contaminate food and feed. One potential method for reducing human health effects due to aflatoxin ingestion is to block uptake via binding by bacteria that either make up the normal gut flora or are present in fermented foods in our diet. These bacteria would bind aflatoxin and make it unavailable for absorption in the intestinal tract. Bifidobacteria comprise a large fraction of the normal gut flora, are thought to provide many probiotic effects and are increasingly used in fermented dairy products. These qualities targeted bifidobacteria for studies to determine if various strains of heat-killed bifidobacteria can bind aflatoxin B1 (AFB1) in vitro. The AFB1 binding affinities of various strains of bifidobacteria, Staphylococcus aureus, and Escherichia coli were quantitated utilizing enzyme-linked immunosorbent and [3H]AFB1 binding assays. The bacteria analyzed were found to bind significant quantities of AFB1 ranging from 25% to nearly 60% of the added toxin. The data also suggest that there are reproducible strain differences in AFB1 binding capacity.

Aflatoxin B1↗

PubMed1990

Five of 12 forms of vaccinia virus-expressed human hepatic cytochrome P450 metabolically activate aflatoxin B1.

Twelve forms of human hepatic cytochrome P450 were expressed in hepatoma cells by means of recombinant vaccinia viruses. The expressed P450s were analyzed for their abilities to activate the potent hepatocarcinogen aflatoxin B1 to metabolites having mutagenic or DNA-binding properties. Five forms, P450s IA2, IIA3, IIB7, IIIA3, and IIIA4, activated aflatoxin B1 to mutagenic metabolites as assessed by the production of His revertants of Salmonella typhimurium in the Ames test. The same P450s catalyzed conversion of aflatoxin B1 to DNA-bound derivatives as judged by an in situ assay in which the radiolabeled carcinogen was incubated with cells expressing the individual P450 forms. Seven other human P450s, IIC8, IIC9, IID6, IIE1, IIF1, IIIA5, and IVB1, did not significantly activate aflatoxin B1 as measured by both the Ames test and the DNA-binding assay. Moreover, polyclonal anti-rat liver P450 antibodies that crossreact with individual human P450s IA2, IIA3, IIIA3, and IIIA4 each inhibited aflatoxin B1 activation catalyzed by human liver S-9 extracts. Inhibition ranged from as low as 10% with antibody against IIA3 to as high as 65% with antibody against IIIA3 and IIIA4. These results establish that metabolic activation of aflatoxin B1 in human liver involves the contribution of multiple forms of P450.

Aflatoxin B1↗

PubMed2000

[In vivo studies of the inhbitory effect of various food components on aflatoxin B1 metabolism].

Possible interferences with aflatoxin B1 metabolism, of some compounds naturally present in food (quercetin, beta-naphthoflavone), resulting from way of cooking method (2-aminodipyrido [1,2-a; 1',2'-d] imidazole (Glu-P-2), norharmane; NH) or used as food additives (butylated hydroxytoluene; BHT) have been studied in vivo by evaluating the production of adducts to glutathione and adducts to serum proteins in laboratory rats. Glu-P-2 and norharmane inhibit strongly the production of adducts to glutathione whereas quercetin and beta-naphthoflavone have only a low effect. BHT is completely ineffective. The adducts to proteins are inhibited by the five compounds, norharmane being the most efficient.

Aflatoxin B1↗

PubMed1991

Contribution of the glutathione S-transferases to the mechanisms of resistance to aflatoxin B1.

The harmful effects of Aflatoxin B1 (AFB1) are a consequence of it being metabolized to AFB1-8,9-epoxide, a compound that serves as an alkylating agent and mutagen. The toxicity of AFB1 towards different cells varies substantially; sensitivity can change significantly during development, can be modulated by treatment with xenobiotics and is decreased markedly in preneoplastic lesions as well as in tumors. Three types of resistance, namely intrinsic, inducible and acquired, can be identified. The potential resistance mechanisms include low capacity to form AFB1-8,9-epoxide, high detoxification activity, increase in AFB1 efflux from cells and high DNA repair capacity. Circumstantial evidence exists that amongst these mechanisms the glutathione S-transferases, through their ability to detoxify AFB1-8,9-epoxide, play a major role in determining the sensitivity of cells to AFB1.

Aflatoxin B1↗

PubMed2000

Non-invasive in vivo magnetic resonance imaging assessment of acute aflatoxin B1 hepatotoxicity in rats.

Acute aflatoxin B1 (AFB1)-induced hepatotoxicity was assessed in vivo in male Sprague-Dawley rats (150-300 g) using magnetic resonance imaging (MRI). MRI results were compared to serum enzyme levels, histology and electron microscopy. Twenty-four hours following intraperitoneal delivery of AFB1 (3 mg/kg body weight in a saline/dimethyl sulfoxide (DMSO; 0.03 ml/kg body weight) solution), regions of damage, characterised by increased proton signal intensities in T2-weighted images, were observed in the vicinity of the hepatic portal vein (HPV) and in the right medial regions of the liver. Image analysis of regions of apparent damage around the HPV and right medial regions, following 24 h of AFB1 exposure, indicated statistically significant (P<0.05) increases in proton image signal intensities, when compared to saline/DMSO-treated rats. No significant difference in proton image signal intensities were observed 1-2 h following AFB1 exposure. Twenty-four hours following AFB1 exposure, histopathological assessment was characterised by portal/central vein/artery congestion, sinusoid congestion, nuclear pyknosis and karyolysis, and hepatocyte vacuolation; electron microscopy (EM) examination indicated nuclear debris, swollen cytoplasmic compartments, vacuolation, and the disappearance of the smooth endoplasmic reticulum, and elevated levels of serum aspartate aminotransferase and alanine aminotransferase were found to be significantly different (P<0.01) than controls.

Aflatoxin B1↗

PubMed2004

Effects of vitamin C and E on liver enzymes and biochemical parameters of rabbits exposed to aflatoxin B1.

Hepatotoxic substances such as aflatoxin B1 (AFB1) produce free radical reactions during biotransformation damage to liver cells. Vitamins C and E are important natural antioxidants suppressing free radicals. This study investigated the effects of vitamins C and E on liver enzymes and other biochemical parameters in rabbits experimentally exposed to AFB1. The first group was control and fed the diet with dimethyl sulfoxide; the second group received 0.1 mg AFB1/kg diet; the third group received vitamin C (100 mg L-ascorbic acid/kg diet); the fourth group received vitamin E (100 mg alpha-tocopherol/kg diet); and the fifth group received vitamin C+vitamin E (100 mg L-ascorbic acid/kg diet+100 mg alpha-tocopherol/kg diet). Diets of the second, third, fourth and fifth groups were mixed with 0.1 mg AFB/kg diet) and feedings were continued for 10 w. Levels of aspartate transaminase, alanine transaminase, alkaline phosphatase, creatine phosphokinase and lactate dehydrogenase after receiving AFB1 were significantly increased, while activities of aspartate transaminase, alanine transaminase, amylase, creatine phosphokinase and lactate dehydrogenase in groups receiving AFB1 + vitamins C, E or C+E were significantly lower than that of the AFB1-alone group. Although of the activity of alkaline phosphatase increased with AFB1 exposure, it decreased with vitamin C administration. Levels of urea, triglyceride, cholesterol and albumin were affected by AFB1 and AFB1+vitaminC. AFB1 affected some liver enzymes and other biochemical parameters, but vitamins C, E and C+E partially prevented an increase in these liver enzymes and some the biochemical parameters induced by AFB1.

Aflatoxin B1↗

PubMed1994

Studies on the binding and transcriptional properties of aflatoxin B1-8,9-epoxide.

[3H]Aflatoxin B1-8,9-epoxide ([3H]AFB1-8,9-epoxide), the putative ultimate carcinogen of AFB1, was synthesized and tested for its binding specificity to and transcriptional effect on several single- and double-stranded DNAs containing cytosine. The test was carried out over a 200-fold concentration range (i.e. 0.1-20 microgram [3H]AFB1-8,9-epoxide per 0.025 A260 units of DNA). The results show: (i) [3H]AFB1-8,9-epoxide bound preferentially to the double-stranded alternating co-polymer poly[d(G-C)] over the double-stranded poly(dG).poly(dC) and single-stranded poly(dG) or poly(dC) homopolymers. (ii) The binding affinity of [3H]AFB1-8,9-epoxide to poly(dC) was essentially the same as the poly(dG). (iii) Under identical conditions, [3H]AFB1-8,9-epoxide bound to poly(dG).poly(dC) 2.5-3 times more than to poly[d(I-C)]; however, poly[d(I-C)]-directed RNA synthesis was clearly more sensitive to [3H]AFB1-8,9-epoxide inhibition than poly(dG).poly(dC). Conversely, the binding affinity of [3H]AFB1-8,9-epoxide to poly(dC) and to poly[d(I-C)] was quite similar, yet poly(dC)-directed RNA synthesis was much more resistant to [3H]AFB1-8,9-epoxide inhibition than poly[d(I-C)]. (iv) After [3H]AFB1-8,9-epoxide was hydrolyzed to [3H]AFB1-8,9-dihydrodiol (0.01 N NaOH, 10 min 23 degrees C), it was no longer able to bind poly[d(G-C)] or to inhibit poly[d(G-C)]-directed RNA synthesis. These results confirm our earlier studies using microsome-activated AFB1 and AFB1-Cl2 that AFB1 after activation is able to bind cytosine in DNA, and the binding is not via AFB1-8,9-dihydrodiol. Furthermore, the results also suggest that AFB1 adducts may not have the same biological effect depending on the base, sequence as well as the conformation of the DNA where the adducts are formed.

Aflatoxin B1↗

PubMed2005

Survey for co-occurrence of ochratoxin A and aflatoxin B1 in dried figs in Turkey by using a single laboratory-validated alkaline extraction method for ochratoxin A.

A survey was carried out to determine the co-occurrence of ochratoxin A and aflatoxin B1 in dried figs from Turkey. Samples from two seasons of crops (2003 and 2004) intended for export to the European Union and the 2004 crop obtained from the domestic Turkish market were analyzed. Affinity column cleanup methods were employed for determining separately ochratoxin A and aflatoxin B1, but for ochratoxin A an alkaline extraction procedure was employed (in contrast to the conventionally employed acidic extraction), which gave consistently higher toxin recovery. In-house validation of the ochratoxin A method gave a limit of detection of 0.15 ng/g and a limit of quantification of 0.5 ng/g with a repeatability of 5.8% in the range 5 to 10 ng/g (with a mean recovery of 94% for spiked samples). Positive results for ochratoxin A were confirmed by liquid chromatography-mass spectrometry. For the 2003 export figs (58 samples), 7 samples contained only aflatoxin B1, 2 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 35.1 ng/g for aflatoxin B1 and 13.0 ng/g for ochratoxin A). Similarly for the 2004 export figs (41 samples), 16 samples contained only aflatoxin B1, 4 samples contained only ochratoxin A, and 2 samples contained both toxins (with maximum concentrations of 20.6 ng/g for aflatoxin B1 and 26.3 ng/g for ochratoxin A). Of 20 retail samples of dried figs from Turkey, only one sample contained ochratoxin A (2.0 ng/g) and none were contaminated with aflatoxin B1. This survey revealed a 14 to 15% incidence of occurrence of ochratoxin A for 2 years, which is higher than previously reported.

Aflatoxin B1↗

PubMedDate not supplied

Aflatoxin B1 and aflatoxicol metabolism in rainbow trout (Salmo gairdneri) and the effects of dietary cyclopropene.

Aflatoxin M1 was identified as a minor metabolite formed by the in vitro incubation of aflatoxin B1 with the postmitochondrial fraction or microsomes from rainbow trout (Salmo gairdneri) liver. Fresh, whole trout liver converted perfused aflatoxin B1 to aflatoxicol and aflatoxin M1, and converted perfused aflatoxicol to aflatoxin B1 and aflatoxin M1. AFB1 reductive activity was found in the 105,000 xg supernatant, while activity converting AFL to AFB1 was distributed about equally in the 105,000 xg supernatant and in the microsomal pellet. Transformation of AFL to AFB1 was not inhibited by CO, but formation of AFM1 was completely blocked. Cyclopropene fatty acids (CPFA)-fed fish produced only one-half to one-third as much AFL from AFB1 as controls, and they produced no detectable AFM1. Most of the unreacted AFB1 was recovered by extraction of the incubation medium by organic solvent whereas, in controls, much of it remained bound to the protein. There was no difference in conversion of AFL to AFB1 when results were expressed in terms of postmitochondrial protein levels. CPFA-fed fish had lower microsomal protein and cytochrome P-450 levels and NADPH-cytochrome c reductase and aldrin epoxidation activities than did controls.

Aflatoxins↗

PubMed2003

The effects of aflatoxin B1 on the development of kwashiorkor in mice.

Seventy Swiss albino mice (6-week-old male) were selected for the investigation into aflatoxin B1's role in the cause of kwashiorkor. The mice were divided randomly into four groups. They were grouped within each group by being fed either low or normal protein level diets supplemented with very small amounts of aflatoxin B1 (0.5 microg/day). The control groups were fed aflatoxin B1-free diets containing either normal or low protein levels. All groups were monitored for 7 weeks. The increase in body weight was found to be low in groups I and II, given diets contaminated with aflatoxin B1. Although groups II and IV, which were given low dietary protein, showed remarkable decreases in serum total protein and albumin levels (group II: total protein 4.1 +/- 0.1 g/dL, albumin 2.6 +/- 0.8 g/dL and group IV: total protein 4.6 +/- 1.3 g/dL, albumin 2.8 +/- 0.82 g/dL) when compared with the groups fed a normal dietary protein level (group I: total protein 5.9 +/- 1.3g/dL, albumin 3.4 +/- 0.7g/dL and group III: total protein 5.4 +/- 1.6g/dL, albumin 3.5 +/- 1.2g/dL; P < 0.05). The statistical difference between these two groups was found not to be significant (P > 0.05). However, decreases in total protein and albumin levels were a little more prominent in group II. In addition, histopatological changes of the liver was remarkable in the group fed a low protein diet and aflatoxin B1 when compared with the group fed only a low protein diet and no aflatoxin B1. More significantly, however, was the increase in liver weight in both groups fed a low protein diet (groups II and IV). Our conclusion is that aflatoxin B1 could not have contributed to the development of kwashiorkor.

Aflatoxin B1↗

PubMed1981

Inhibitory effect of molybdenum and vanadium salts on aflatoxin B1 synthesis by Aspergillus flavus.

The effects of the elements zinc, manganese, iron, copper, molybdenum, and vanadium, added in various salt forms, on mycelial weights and aflatoxin B1 accumulation in the mycelium of Aspergillus flavus were investigated in liquid shake cultures. Ammonium heptamolybdate, when added to a complete medium at concentrations of 50-100 mg/L, appreciably reduced aflatoxin B1 accumulation without affecting growth of the fungus. Sodium molybdate and sodium monovanadate also reduced aflatoxin B1 yields without affecting mycelial growth but to a lesser extent. The addition of zinc sulphate stimulated aflatoxin B1 production in all media used. The influence of the other trace elements on aflatoxin production depended on the level of trace elements present in the basal medium. In general, manganese chloride had a stimulatory effect, whereas copper sulphate depressed yields. Mycelial levels of aflatoxin had peaked and then declined before mycelial dry weights had reached maximum. High yields of aflatoxin B1 were obtained in media having a final pH as low as pH 2.8.

Aflatoxin B1↗