Mahendra Rai

By Mahendra Rai, Indarchand Gupta, Shital Bonde, Pramod Ingle, Sudhir Shende, Swapnil Gaikwad, Mehdi Razzaghi-Abyaneh and Aniket Gade

There is a great demand for green methods of synthesis of nanoparticles. Fungi play an important role in the synthesis of nanoparticles, of which Aspergillus spp. are known to secrete different enzymes responsible for the synthesis of nanoparticles. The process of biosynthesis of nanoparticles is simple, rapid, cost-effective, eco-friendly, and easy to synthesize at ambient temperature and pressure. Mostly, the metal nanoparticles such as silver, gold, lead and the oxides of titanium, zinc, and copper are synthesized from Aspergillus spp. These include mainly Aspergillus fumigatus, A. flavus, A. niger, A. terreus, and A. clavatus. The fabrication of different nanoparticles is extracellular. In the present chapter, we have discussed the role of different species of Aspergillus, mechanism of biogenic synthesis particularly enzymes involved in the reduction of metal ions into nanoparticles. The biogenically synthesized nanoparticles have demonstrated several biomedicals, agricultural, and engineering applications. The biogenic nanoparticles are mostly used as antimicrobial and cytotoxic agents. Their use as fungicidal agents is important for sustainable agriculture.

Part of the book: The Genus Aspergillus

By Fatemehsadat Jamzivar, Mohammad Ali Ebrahimi, Mohammadhassan Gholami-Shabani, Zahra Salehi, Golamreza Bakhshi-Khaniki, Masoomeh shams-Ghahfarokhi, Ali Eslamifar, Mahendra Rai, Mehdi Razzaghi-Abyaneh

In the present study, 203 strains of Aspergillus flavus isolated from pistachio soil orchards of Iran were studied for vegetative compatibility groups (VCGs). A. flavus strains were cultured on potato dextrose Agar plates and transferred to Czapek Dox Agar (Cz) contained potassium chlorate. For nit mutant generation, cultures were transferred to nitrate-free Cz contained each of ammonium tartrate, hypoxanthine and sodium nitrate separately. Nit mutants grown on theses media were assigned as nirA, cnx, and niaD, respectively. Evidence of a white thick mass of fungal growth in the border of strains indicated the compatibility of the corresponding strains. Out of 203 studied A. flavus strains, 22 strains had VCGs distributed in nine groups from A to I based on pairing patterns. Of 22 VCG positive strains, 16 produced aflatoxin B₁, and 11 of 22 strains produced cyclopiazonic acid as evidenced by chromatography. All 22 A. flavus strains were categorized in 4 different chemotypes based on mycotoxins production pattern. Phylogenetic study of 22 VCG positive A. flavus strains using specific primers of ITS and ß-tubulin genes on fungal DNA were performed. Results of dendrograms indicated that 22 A. flavus strains were distributed in three separate clusters and several subclusters. Taken together, results of the present study indicated that A. flavus strains have various patterns of mycotoxins (aflatoxin and cyclopiazonic acid) production as well as VCGs, which can be correlated in some extents with fungal phylogeny.

Part of the book: Sustainable Crop Management