Potential of an endophytic fungus Alternaria tenuissima PE2 isolated from Psidium guajava L. for the production of bioactive compounds
2022
Chatterjee, Sohini | Ghosh, Suvranil | Mandal, Narayan Chandra
Searching of novel bioactive compounds from natural sources is increasing day by day for overcoming multidrug resistant microorganisms and endophytic fungi are considered as important sources in this regard. In the present study, one potent endophytic fungal isolate PE2 was isolated from the leaves of Psidium guajava L. which was identified as Alternaria tenuissima by 28S rDNA sequence homology. The isolate was found to produce thermostable, non-proteinacious antimicrobial substances. Ethyl acetate (EA) extract of the cell free supernatant (CFS) of the isolate was found effective against both Gram-positive and Gram- negative bacteria with MIC values of ∼500 µg/mL and ∼800 µg/mL, respectively. Degradations of bacterial cells upon treatment were supported by the release of intracellular materials as well as scanning electron microscopic (SEM) studies. EA extract also exhibited an adverse effect on bacterial central carbohydrate metabolic pathway enzymes viz. phospho fructokinase, isocitrate dehydrogenase and fructose-1,6-bisphosphatase. Production of inhibition zones against pathogenic fungi including human pathogenic yeast Candida albicans, inhibition of fungal radial growth and conidial germination upon treatment suggested antifungal potential of the EA extract of the isolate. SEM study revealed massive deformation of cellular integrity of C. albicans, indicated the probable effect of antimicrobial compounds. Thin layer chromatographic (TLC) separation and GC-MS analysis revealed the production of numbers of bioactive compounds by the isolate. Based on the present study, isolate Alternaria tenuissima PE2 could be considered as a promising source of natural bioactive metabolites.
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