Molecular Identification, Mycelial Growth Kinetics, and Antimicrobial Potential of Newly Isolated Medicinal Mushroom Fomitopsis pinicola from Bulgaria.

The present study is focused on a newly isolated Fomitopsis strain obtained from black pine (Pinus nigra) from the Sredna Gora Mountains, Bulgaria. Molecular identification, based on ITS1-5.8S-ITS2 region sequencing, confirmed the strain as Fomitopsis pinicola with 99.84 BLAST percent identity. Phylogenetic analysis verified that the new fungal isolate belongs to the European F. pinicola clade. The morphological analysis of the strain revealed several distinctive structures that further support its identification. The influence of culture media composition on fungal development was evaluated by analyzing the mycelial growth kinetics using both the logistic growth model and the reversible autocatalytic model. Submerged cultivation was employed to produce fungal biomass, which was subsequently lyophilized and used for the assessment of the antimicrobial potential of the fungal strain. The results demonstrated notable antimicrobial effects against all tested bacterial strains. The most significant activity was observed for the aqueous extract against Escherichia coli and the hexane extract against Salmonella enteritidis, both with a minimum inhibitory concentration of 312.5 µg/mL. These findings highlight the promising potential of the newly isolated F. pinicola strain for future applications in the medical and pharmaceutical industries, particularly in developing drugs to combat multidrug resistance, based on the promising results of its water extracts.