Fascinating Potential of Aspergilli

Aspergillus species are of immense interest to scientific community due to biological, ecological and metabolic diversity. Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger play key role in the clinical manifestation of a spectrum of Aspergillus induced diseases both in immunocompetent and immunocompromised hosts. Several novel allergens of A. fumigatus are identified and characterized some of which have diagnostic relevance. The role of some of these allergens in immune mechanisms and immunopathogenesis are examined in detail and the host pathogen interactions are well established. A. oryzae and A. niger are industrially useful in view of their use in the production of soy sauce, citric acid, and enzymes such as glucose oxidase and lysozyme etc. These two species are also used as hosts for production of heterologous proteins of clinical importance. A. flavus and A. parasiticus produce aflatoxins, and sterigmatocystin that are highly potent, naturally occurring toxins known to humans. Aflatoxin contamination in the agricultural crops and agri-products is an important challenge to the scientists in view of the WTO stipulations. The permissible limit of Aflatoxin is 4‐20 ppb in the food and food products in international trade. Several important mycotoxins of Aspergillus species include Aflatoxins, Sterigmatocystin, Ochratoxin, Cyclopiazonic Acid, etc. Melanin, a pigment produced by A. fumigatus is attributed to the virulence of the pathogen and the disease. It is interesting to note that A. fumigatus secretes a variety of toxins such as gliotoxin, an immune suppressor and a protein toxin Aspf1, which is a multifunctional protein exhibiting IgE and IgG inducing properties with ribonuclease activity and cytotoxic properties, besides an