Title : Molecular identification, mycelial growth kinetics and antimicrobial potential of newly isolated medicinal mushroom Inonotus hispidus from Bulgaria
Abstract:
Inonotus hispidus is a well-known edible and medicinal mushroom known for its nutritional and therapeutic properties. Because of its enormous biosynthetic potential, over the past 5 years this basidiomycete fungus has attracted the attention of the scientific community. The present study is focused on a newly isolated Inonotus hispidus strain from an apple tree (Malus domestica) from Haskovo province, Bulgaria. The molecular identification of the isolate was conducted by amplification of ITS1-5.8S-ITS2 region and the strain was identified as Inonotus hispidus with 99.12% of confidence. The morphological examination revealed the presence of some specific structures supplementing the morphological characteristics of the fungus. The phylogenetic analysis was conducted using the closest matched ITS sequences from the GenBank database. The presented results showed the phylogenetic relationship between the examined I. hispidus strain and other I. hispidus strains, as well as other species of genus Inonotus. The effect of nutrient media composition was evaluated by determination of the mycelial growth kinetics, applying the logistic curve model and the reverse autocatalytic growth model. Based on the obtained data, MEA (malt extract agar) was assessed as the most suitable media for in vitro cultivation. In addition, the optimal temperature and pH values for cultivation were determined. The best conditions for the newly isolated Inonotus hispidus strain growth were t = 28°C and pH = 6.5. Submerged cultivation was carried out to obtain biomass, which was further lyophilized and used for assessment of the antimicrobial potential of the fungal strain. The data demonstrated significant antimicrobial activity against all tested bacterial and yeast strains. The best results were achieved for the hot water and hexane extracts against Staphylococcus aureus ATCC 25923, where the minimal inhibitory concentration (MIC) was 0.3125 mg/mL. Similar data was observed for the hexane extract against Klebsiella pneumoniae ATCC 13883 and butanol extract against Escherichia coli ATCC 8739 (MIC = 0.3125 mg/mL). The obtained results reveal the vast potential of the newly isolated medicinal mushroom Inonotus hispidus for further application in medical and pharmaceutical industry.
