Shodieva, D.; Abdulmyanova, L.; Gulyamova, T.; Ruzieva, D.; Kuzieva, N.; Annaev, M.; Siddikova, S.; Mahkamov, S.

Endophytic yeasts of the Metschnikowia pulcherrima clade are recognized as natural producers of pulcherrimin, an iron-chelating red pigment associated with antimicrobial activity. However, endophytic isolates from arid Central Asian fruit trees remain unexplored, and their pulcherrimin biosynthetic capacity is poorly characterized. In this study, five endophytic M. pulcherrima strains were isolated from apricot, persimmon, peach and pomegranate fruits in Uzbekistan and identified using MALDI-TOF MS and ITS sequencing. The strains were cultivated in FeCl3-supplemented Sabouraud medium, and pulcherrimin was extracted and quantified using a gravimetric workflow with biological triplicates. Pigment yields ranged from 420.6 to 776.4 mg/L, representing some of the highest values reported for non-engineered isolates under flask conditions. Antimicrobial activity was evaluated by agar well diffusion assays against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans, with inhibition zones reaching 18-23 mm depending on the strain. Nano-LC-MS/MS analysis confirmed the presence of key intermediates of the pulcherrimin biosynthetic pathway, including cyclo(Leu-Leu) and pulcherriminic acid, supporting the metabolic origin of the pigment. These findings reveal that endophytic M. pulcherrima from Uzbekistan fruit trees and shrubs constitute highly productive natural sources of pulcherrimin and represent promising candidates for future fermentation optimization and development of natural antimicrobial pigments.