Biosynthesis of aflatoxin B1. Conversion of versicolorin A to aflatoxin B1 by Aspergillus parasiticus

1976 ◽  
Vol 24 (6) ◽  
pp. 1167-1170 ◽  
Author(s):  
Louise S. Lee ◽  
Joan W. Bennett ◽  
Alva F. Cucullu ◽  
Robert L. Ory
Keyword(s):  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Versicolorin A

scholarly journals Production of aflatoxins and aflatoxicols by Aspergillus flavus and Aspergillus parasiticus and metabolism of aflatoxin B1 by aflatoxin-non-producing Aspergillus flavus.

Eisei kagaku ◽  
1991 ◽  
Vol 37 (2) ◽  
pp. 107-116 ◽  
Author(s):  
MITSUO NAKAZATO ◽  
SATOSHI MOROZUMI ◽  
KAZUO SAITO ◽  
KENJI FUJINUMA ◽  
TAICHIRO NISHIMA ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus

Secondary biosynthesis of aflatoxin B1 in Aspergillus parasiticus

1970 ◽  
Vol 16 (10) ◽  
pp. 959-963 ◽  
Author(s):  
R. W. Detroy ◽  
C. W. Hesseltine
Keyword(s):  
Protein Synthesis ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Synthetase Activity ◽  
Macromolecular Synthesis ◽  
High Concentration ◽  
Methyl Group ◽  
Aflatoxin B ◽  
Concentration Levels

The effect of two inhibitors on the formation of aflatoxin B1 synthetase activity in strain NRRL 2999 Aspergillus parasiticus has been studied. Aflatoxin B1 synthesizing activity was measured in vivo by incorporation of the 14C-methionine methyl group into aflatoxin B1. Cycloheximide at a concentration of 150 μg/ml blocks protein synthesis completely. If addition of cycloheximide is made before B1 synthetase appears, no activity accumulates; if added during accumulation, activity is frozen at the level reached at the time of addition. The cycloheximide effect is reversible since morphogenesis, total protein synthesis, and aflatoxin B1 synthetase activity all resume after removal of the inhibitor.DL-p-Fluorophenylalanine partially inhibits aflatoxin B1 synthesis in vivo; however, its effect upon macromolecular synthesis is incomplete even at high concentration levels. Once formed, the aflatoxin synthetase appears to maintain B1 synthesis when further protein synthesis is blocked; i.e., it is not rapidly degraded.

Effects of Potassium Sorbate on Growth and Aflatoxin Production by Aspergillus parasiticus and Aspergillus flavus1

1983 ◽  
Vol 46 (11) ◽  
pp. 940-942 ◽  
Author(s):  
LLOYD B. BULLERMAN
Keyword(s):  
Aspergillus Flavus ◽  
Yeast Extract ◽  
Aflatoxin B1 ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Aspergillus Parasiticus ◽  
Aflatoxin Production ◽  
Potassium Sorbate ◽  
Mycelial Mass ◽  
Yeast Extract Sucrose

Growth and aflatoxin production by selected strains of Aspergillus parasiticus and Aspergillus flavus in the presence of potassium sorbate at 12°C were studied. Potassium sorbate at 0.05, 0.10 and 0.15% delayed or prevented spore germination and initiation of growth, and slowed growth of these organisms in yeast-extract sucrose broth at 12°C. Increasing concentrations of sorbate caused more variation in the amount of total mycelial growth and generally resulted in a decrease in total mycelial mass. Potassium sorbate also greatly reduced or prevented production of aflatoxin B1 by A. parasiticus and A. flavus for up to 70 d at 12°C. At 0.10 and 0.15% of sorbate, aflatoxin production was essentially eliminated. A 0.05% sorbate, aflatoxin production was greatly decreased in A. flavus over the control, but only slightly decreased in A. parasiticus.

Preparation of 14C-Labeled Aflatoxin B1

1973 ◽  
Vol 56 (3) ◽  
pp. 643-646
Author(s):  
Grant L Schoenhard ◽  
Russell O Sinnhuber ◽  
Donald J Lee
Keyword(s):  
Trace Metals ◽  
Primary Culture ◽  
Silica Gel ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Specific Activity ◽  
Ultraviolet Spectrum ◽  
Reference Standard ◽  
Chemical Purity ◽  
Chloroform Methanol

Abstract A successful method to obtain 14C-labeled aflatoxin B1 from Aspergillus parasiticus ATCC 15517 was developed. The nitrogen-free resting culture contained mycelia from a 72 hr primary culture, 0.02M glucose, 0.005M (1 mCi/mmole) acetate-1-14C, salts, and trace metals. It was incubated 12 hr at 30°C. Aflatoxin B1-14C was isolated from chloroform extracts of the resting culture by column chromatography on silica gel H eluted under pressure with a continuous gradient of chloroform to chloroform-methanol (98+2). The ultraviolet spectrum of the 14C-labeled aflatoxin was examined. The ratios of the absorbances at 220/265 and 362/265 nm compared to established values and a reference standard were used as criteria of chemical purity. Label integrity was verified by chromatography, hydrogenation to the tetrahydrodeoxoaflatoxin B1, and conversion to the hemiacetal and the epimeric acetates. After purification, 1.37 mg 14C-labeled aflatoxin B1 of specific activity 744 μCi/mmole was obtained from 2 mCi acetate-1-14C of specific activity 1 mCi/mmole.

Individual reaction requirements of two enzyme activities, isolated from Aspergillus parasiticus, which together catalyze conversion of sterigmatocystin to aflatoxin B1

1987 ◽  
Vol 33 (12) ◽  
pp. 1108-1112 ◽  
Author(s):  
Thomas E. Cleveland ◽  
Deepak Bhatnagar
Keyword(s):  
Aflatoxin B1 ◽  
Enzyme Activities ◽  
Microsomal Fraction ◽  
Aspergillus Parasiticus ◽  
Heat Treated ◽  
Individual Reaction ◽  
Aflatoxin B

Individual reaction requirements were determined for each of two enzyme activities present in Aspergillus parasiticus mycelia which together catalyze conversion of sterigmatocystin (ST) to aflatoxin B1 (AFB1). A postmicrosomal activity (PMA) catalyzed conversion of ST to O-methylsterigmatocystin (OMST) and a microsomal activity (MA) catalyzed conversion of OMST to AFB1. PMA was stimulated two- to three-fold in the presence of S-adenosylmethionine. Addition of NADPH promoted the maximum MA; this activity was not detected when FAD, FMN, NAD, or NADH were utilized individually as cofactors in reaction mixtures. A substantial amount (62%) of MA was lost during isolation of the microsomal fraction, but the activity was completely restored by reconstitution with a heat-treated (100 °C) postmicrosomal fraction. The reaction catalyzed by MA was optimum at pH 7.0 and at 17–23 °C, whereas the PMA reaction was optimum at pH 8.0–8.5 and at 35–40 °C. Apparent Km values of approximately 2.6 × 10−6 M (for ST) and 6.6 × 10−7 M (for OMST) were determined for PMA and MA, respectively.

Growth and Aflatoxin Production by Aspergillus parasiticus NRRL 2999 in the Presence of Acetic or Propionic Acid and at Different Initial pH Values

1987 ◽  
Vol 50 (11) ◽  
pp. 909-914 ◽  
Author(s):  
GULAM RUSUL ◽  
FATHY E. EL-GAZZAR ◽  
ELMER H. MARTH
Keyword(s):  
Acetic Acid ◽  
Propionic Acid ◽  
Aflatoxin B1 ◽  
Maximum Concentration ◽  
Aspergillus Parasiticus ◽  
Dry Weight ◽  
Aflatoxin Production ◽  
Lag Phase ◽  
Significant Difference ◽  
Initial Ph

Experiments were done to determine effects of different concentrations of acetic or propionic acid in a glucose-yeast extract-salts medium with an initial pH value of 4,5 or 5.5 on growth and aflatoxin production by Aspergillus parasiticus NRRL 2999. Amounts of aflatoxin were measured with reversed-phase high-performance liquid chromatography. The maximum concentration of acetic or propionic acid that permitted growth at an initial pH of 5.5 was 1% after 7 d of incubation and 0.25% after 3 d of incubation, respectively. When the initial pH of the medium was 4.5, the maximum concentration of acetic or propionic acid that permitted growth was 0.25 or 0.1%, respectively. There was no significant difference (p>0.05) in amount of mycelial (dry weight) produced by cultures in the presence of 0.0, 0.25, 0.50 or 0.75% acetic acid. Amounts of aflatoxin B1 and G1 produced decreased with an increasing concentration of acetic acid. Increasing concentrations of propionic acid caused a decrease in the amount of mycelial dry weight and aflatoxin produced by cultures growing in the medium with an initial pH of 5.5. At an initial pH of 4.5 mycelial growth was slow and at 3 d of incubation amounts of aflatoxin B1 and G1 produced were reduced as concentrations of acetic acid increased. This also was true for propionic acid in the medium with an initial pH of 4.5. Cultures with an extended lag phase in the presence of acetic or propionic acid overcame this and then produced large amounts of aflatoxin B1 and G1 at 7 and 10 d of incubation.

Effect of Dichlorvos on Aflatoxin and Versicolorin a Production in Aspergillus parasiticus

1976 ◽  
Vol 137 (4) ◽  
pp. 318-324 ◽  
Author(s):  
J. W. Bennett ◽  
L. S. Lee ◽  
A. F. Cucullu
Keyword(s):  
Aspergillus Parasiticus ◽  
Versicolorin A

Inhibition of aflatoxin B1, B2, G1 and G2 production by Aspergillus parasiticus in nuts using yellow and oriental mustard flours

Food Control ◽  
2015 ◽  
Vol 47 ◽  
pp. 154-160 ◽  
Author(s):  
C. Hontanaya ◽  
G. Meca ◽  
F.B. Luciano ◽  
J. Mañes ◽  
G. Font
Keyword(s):  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Oriental Mustard
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