Antibacterial activity of endophytic fungi isolated from conifer needles

Abstract

Fungi, in particular endophytes are a promising source of new antimicrobial compounds. The aim of this study was to screen the extracts of conifer needle fungal endophytes for antimicrobial activity and taxonomically place fungi producing ones to determined active metabolites. Seventy three strains of endophytic fungi were isolated from plant samples, mainly from needles of conifers, and cultured. Extracts of cultured endophytic strains were tested for antimicrobial properties using a microdilution assay. Their activity was compared to that of the antibiotic ampicillin. Samples that exhibited antimicrobial properties were further examined. Genomic DNA from five active fungal strains was isolated and species-specific DNA regions (ITS regions) were amplified and sequenced allowing us to determine the identity of the samples. Active endophytic fungi were two strains of Lophodermium pinastri, two strains of Lophodermium seditiosum and one of Phoma herbarum. All of these strains are known as parasitic and can be treated as endophytes only according to the lack of symptoms in their host tissue. This work demonstrates an interesting bottom-up approach to the discovery of new antimicrobial compounds.
 
Key words: Endophyte, antibiotic, parasitic, Lophodermium, antimicrobial, Phoma.