Pestalotiopsis pauciseta

Pestalotiopsis pauciseta is an endophytic fungus isolated from the leaves of medicinal plants in tropical climates. It is notable for producing paclitaxel (Taxol), a billion-dollar anticancer drug. The fungal-taxol produced by P. pauciseta is comparable to standard Taxol, which is used to treat cancers such as ovarian, lung, breast, and head and neck cancers.

Originally described as *Pestalotia pauciseta* by Pier Andrea Saccardo in 1914, the species was reclassified into the genus *Pestalotiopsis* by Chen and Wei in 1993. Microscopic features include amphigenous pustules that are globose to lenticular, black, scattered, and hemispherical (80-200 μm). The conidiomata are eustromatic, cupulate, and initially dark brown when immersed, becoming erumpent, thick-walled, and irregularly dehiscent upon eruption.

Pestalotiopsis species are often saprobes in soil, degraders of plant matter, or pathogens. They can also exist as endophytes in plant leaves and twigs. P. pauciseta has been isolated from dead leaves, bark, twigs, polluted stream water, and is associated with the deterioration of wood, paper, fabrics, and wool. It likely exhibits both endophytic and pathogenic life stages.

The genus Pestalotiopsis is known for producing bioactive compounds, including antifungal, anticancer, antimicrobial, and antitumor agents. Over 130 unique compounds have been isolated from various species. P. pauciseta is suspected to produce bioactive compounds originally derived from its host plants, in addition to fungal-taxol, which has a UV absorption spectrum similar to standard Taxol (maxima at 235 nm and 232 nm).