Aflatoxins biosynthesis

Enzymology and molecular biology of aflatoxin biosynthesis 97CRV2537. 

Three generic approaches for all aflatoxin-susceptible crops could be used to exclude toxigenic fimgi from their environmental niches and to regulate aflatoxin biosynthesis ... 

Other naturally derived aflatoxin inhibitors obtained from the "neem" tree have been investigated in our laboratory (84), Azadirachta indica Juss. commonly known as "margosa" or "neem" is an ornamental tree of Asia and Africa that produces natural products having reputed value for their medicinal, antiviral, antibacterial, insecticidal, antifungal and antinematode properties (86, 87). Several active principles from different parts of the neem tree have been reported (88). Our investigation (84) examined the effects of these neem leaf components in neem leaves on aflatoxin biosynthesis by either Aspergillus parasiticus or A. flavus. 

Inhibition of aflatoxin biosynthesis by neem extracts in fungal cells appear to occur in the very early stages of the biosynthetic pathway (i.e., prior to norsolorinic acid synthesis) because after the initiation of secondary metabolism, the inhibitory effect of the neem leaf constituents was lost (84). 

Several approaches are being explored and developed using new methods in biotechnology to eliminate pre-harvest aflatoxin contamination of food and feed. These approaches resulted from recent information acquired on 1) non-aflatoxigenic A. flavus strains that prevent aflatoxin contamination of cottonseed when co-inoculated with aflatoxigenic strains, 2) molecular mechanisms governing aflatoxin biosynthesis, and 3) plant-derived metabolites that inhibit aflatoxin biosynthesis. 

Bhatnagar, D. and Qeveland, T. E. "Aflatoxin biosynthesis developments in chemistry, biochemistry and genetics" la Aflatoxin in corn New perspectives, Shotwell, O. L. and Hurbuigh, Jr., C. R., Eds Iowa State University Press Ames, lA, 1991, pp. 391-405. 

Minto RE and Townsend CA (1997) Enzymology and molecular biology of aflatoxin biosynthesis. Chem Rev 97, 2537-2555. 

Trail F, Mahanti N, Linz J Molecular biology of aflatoxin biosynthesis. Microbiology 1995 141 755-765. 

Payne GA, Brown MP Genetics and physiology of aflatoxin biosynthesis. Annu Rev Phytopathol 1998 36 329-362. 

Chang P-K, Ehrlich KC, Yu J, Bhatnagar D, Cleveland TE Increased expression of Aspergillus parasiticus aflR, encoding a sequence-specific DNA-binding protein, relieves nitrate inhibition of aflatoxin biosynthesis. Appl Environ Microbiol 1995 61 2372-2377. 

Payne GA, Nystrom GJ, Bhatnagar D, Cleveland TE, Woloshuk CP Cloning of the afl-2 gene involved in aflatoxin biosynthesis for Aspergillus flams. Appl Environ Microbiol 1993 59 156-162. 

Very recent studies have indicated that an essential ingredient in aflatoxin biosynthesis was the fungal pigment averufm (160)110 171. Indeed, it was also shown172-174 that the bisfuran ring system in aflatoxin was concieved by the rearrangement175-177 of the C-6 averufin side chain, rather than by fission, followed... 

McGuire, S. M., Silva, J. C., Casillas, E. G., Townsend, C. A., Purification and characterization of versicolorin B synthase from Aspergillus parasiticus. Catalysis of the stereo differentiating cyclization in aflatoxin biosynthesis essential to DNA interaction. Biochemistry 1906, 35, 11470-11486. 

Buchanan, R. L. and Lewis, D. F. 1984. Regulation of aflatoxin biosynthesis Effect of glucose on the activities of various glycolytic enzymes. Appl. Environ. Microbiol. 48, 306-310. Buchanan, R. L., Federowicz, D., and Stahl, H. G. 1985. Activities of tricarboxylic acid cycle... 

Aspergillus flavm Genomics for Discovering Genes Involved in Aflatoxin Biosynthesis... 

The aflatoxin biosynthesis can be described in two major stages the early and later stages. The early stage aflatoxin intermediates are colored pigments (brick red, yellow, or orange in color), which covers from acetate to VERA. 

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