Isolation and characterization of halophilic soil fungi from the salt desert of Little Rann of Kutch, India

Extremophiles are considered a cornucopian source of chemically diverse and often novel metabolites. Determination of their growth and distribution pattern and their chemical nature is therefore vital to fully gauge their existential uniqueness and potential as a fount of novel compounds. Present study deals with growth characterization and chemoprofiling of halophilic fungi inhabiting a hitherto unexplored terrain of Little Rann of Kutch, India. Thirty five morphologically discrete fungi, primarily belonging to phylum Ascomycota, were isolated from the soil, suggestive of the region’s low microbial diversity. Calculation of fungal salt tolerance index identified one isolate as a halophile with the remaining being halotolerant. Morphological characteristics and 18S rDNA sequencing established the halophile’s identity as Aspergillus versicolor. A. versicolor was further characterized for its salt tolerance potential and degree of halophily. The fungus grew optimally at 7.5% NaCl, thereby classifying it as a moderate halophile. Macro-morphology of the fungus corresponded well with its micro-morphology. At 0% and 10% NaCl, fungal specimen exhibited mycelial distortions, loss of cytoplasm and sparse conidiation; healthy growth features were observed at 7.5% NaCl. For chemoprofiling, A. versicolor was cultured on Czapek Dox broth and Malt Extract broth and the crude extract was analysed by liquid chromatography mass spectrometry (LC-MS). A comparative chemoprofile analysis determined Czapek Dox broth to be a better choice for profiling of this particular strain as it exhibited higher compound diversity. The rich chemical contour of A. versicolor suggests the fungus to be a potential source of novel bioactive molecules of pharmaceutical significance.