Endophytic fungi associated with high-altitude Juniperus trees and their antimicrobial activities

Fungal endophytes were isolated from twigs of Juniperus procera (Cupressaceae) collected from Taif region (Saudi Arabia). Twenty-six different taxa were recovered. The overall foliar colonization rate was 36%. A total of 144 isolates were obtained and identified into six distinct operational taxonomic units based on the sequencing of the internal transcribed spacer regions of the rRNA gene. The most prevalent fungi were Aspergillus fumigatus, Penicillium oxalicum, Preussia sp., Peyronellaea eucalyptica, Peyronellaea sancta and Alternaria tenuissima. A total of 144 isolates were tested for antibacterial and antifungal activities against Staphylococcus aureus, Klebsiella pneumoniae, Candida albicans and Fusarium solani in which 52 isolates showed antimicrobial activity against at least one of the tested microbes. Aspergillus fumigatus (7 isolates), Hypocrea lutea (4), Penicillium oxalicum (10) and Preussia sp. (5) presented the strongest antimicrobial activity. This study confirmed the variation of different isolates of the same species in terms of antibacterial activity. Also, it indicated that the endophytic fungi of Juniperus procera plants should be another potential source of bioactive antimicrobial agents.