Morphological and toxigenic study of Aspergillus flavus from indoor air

Abstract

Aim: In the current investigation thirty four A. flavus cultures were isolated from indoor air samples of some farmers' house in coastal region of Odisha. Production of aflatoxin B1 and the pattern of formation of sclerotia by the isolates were studied in vitro. Methodology: Morphological study and production of sclerotia were carried out by observing fungal colonies on culture media. Conidiophores were identified under Phase contrast microscope. Detection of aflatoxin B1 was done by Thin Layer Chromatography technique. Results: The isolates exhibited variation in their colony characteristics and pattern of sclerotia formation. Overall 44% A. flavus isolates produced stable aflatoxin B1 and 41% were producers of sclerotia. About 32% A. flavus isolates produced both sclerotia and aflatoxin B1. Most of the non toxigenic isolates failed to form thick mycelia mat on β-CD-PDA media. Aflatoxin and sclerotia producing isolates were found more in coastal districts than inter-coastal regions. No significant variation in the pattern of sclerotia production was observed among isolates in less aerobic (sealed plates) and aerobic (unsealed plates) condition, however isolates had slightly more preference towards less aerobic environment for sclerotia production. The size of sclerotia was found to be inversely related to number of sclerotia. ne C