In vitro Antimicrobial
activity and Qualitative Enzymatic assays of Cladosporium pseudocladosporidiales,
AVNK4, an endophytic fungus isolated from seeds of Nigella sativa
Shaik Mahekal Kousar, Krishnaveni Vunnam and Amrutha Valli Audipudi
Res. J. Biotech.; Vol. 20(11); 300-309;
doi: https://doi.org/10.25303/2011rjbt3000309; (2025)
Abstract
Endophytes are vital reservoirs of bioactive compounds with pharmaceutical and industrial
significance. This study reports isolating and characterising a novel fungal endophyte,
AVNK4, from surface-sterilised Nigella sativa seeds, identified as Cladosporium
pseudocladosporidiales using morphological observations and ITS-rDNA sequencing.
AVNK4 is the first reported isolate of Cladosporium pseudocladosporidiales from
Nigella sativa seeds, showing both diverse lytic enzyme production and broad-spectrum
antimicrobial activity against human and plant pathogens. Ethyl acetate extracts
exhibited strong inhibition zones and low minimal inhibitory concentrations, indicating
potent bioactivity. Enzymatic assays revealed substantial production of cellulase,
amylase and protease, which enhance the endophyte’s bioactive potential. These hydrolytic
enzymes enhance the endophyte’s bioactive potential by degrading cell walls and
assisting in metabolite delivery, synergising with antimicrobial compounds.
Furthermore, some enzymes are directly involved in secondary metabolite biosynthesis
such as non-ribosomal peptide synthetases and polyketide synthases, which are responsible
for the production of antibiotics and antifungals. The dual functionality of AVNK4,
as a producer of both antimicrobial metabolites and industrially relevant enzymes,
underscores its promise for biotechnological applications in pharmaceuticals, agriculture
and enzyme-based industries as novel drugs and biocatalysts. This study lays the
foundation for further metabolite purification and mechanistic investigations to
support drug development and industrial enzyme deployment.
