Isolation of endophytic fungi and actinomycetes taxane producers

The fungal and actinomycete populations of internal tissues of woody branches, shoots and leaves of different plants belonging to the genus Taxus were investigated. 22 plants of Taxus baccata and one of Taxus brevifolia were sampled in different habitats located in central-northern Italy. 150 fungal and 71 actinomycete strains were isolated, some of them from woody tissues, others from herbaceous ones. Both microbial populations are composed of representatives of different genera and for the first time the presence of actinomycetes inside living tissues of plant above-ground organs is reported. Fungi and actinomycetes were screened for taxane production. Different liquid media were used for strain growth and the culture extracts were assayed by a competitive inhibition enzyme immunoassay (CIEIA) using a commercial kit employing a polyclonal antibody. The production of taxanes was detected in 15 out of 150 fungal strains and in 10 out of 71 actinomycetes, isolated both from woody and herbaceous tissues. In both populations, the production of taxanes was quantitatively low and only in few cases reached the 50-100 ng per litre. The capability to produce taxanes seems not to be related to the geographical origin of isolation sources of the fungal taxon but with a particular tree from which the fungus was isolates.