Endophytic Fungi Are Multifunctional Biosynthesizers 55potential use for pharmaceutical applications (Strobel, 2003; and Selim et al.,
2012). A background understanding that involves some specific examples and
rationale of the presence of endophytic microorganisms in higher plants will
aid in the development of a drug discovery program involving these
organisms.
9.1. Endophytes Producing Anticancer Compounds
A search for a rare and a costly product such as taxol may be facilitated by
investigating the endophytic microbes of plants that are able to synthesize this
compound. Taxol is found in all Taxus sp., (yew trees) and it is belong to
diterpenoid compounds (Stierle et al., 1993).
This compound is the world’s first billion dollar anticancer drug and it is
used to treat a number of cancer diseases. Due to its high price it is not readily
available to worldwide. Thus, alternative sources are required for producing
reasonable amounts of such important drug (Stierle et al., 1993 and Strobel,
2006). In fact, all world’s higher plants contain certain endophytic species,
thus, it may be possible that yew trees might be a shelter for a certain
endophytes that can synthesize taxol. Thus, with the availability of microbial
source that is able to produce this drug, the need to harvest the slow-growing
and relatively rare yew trees is eliminated (Strobel, 2006). The taxol price
would be much cheaper, since it can be produced via fermentation like
penicillin production. It was speculated that the ability of any endophyte to
make taxol may have arisen with a gene transfer from the yew tree to one or
more of endophytes living in close association with it. Until early 1990s, no
endophytic fungi had been recorded from any of the world’s representative
yew species. After several years of effort a novel taxol-producing endophytic
fungus Taxomyces andreanae was identified from Taxus brevifolia (Strobel et
al., 1993 and Selim et al., 2012).
9.2. Endophytes Producing Antibiotics
The imperfect stage of Pezicula cinnamomea is a fungus identified as
Cryptosporiopsis cf. quercina, which is frequently associated with hard wood
species. This fungus and related species are always found worldwide as
endophytes. In 1999, it was isolated as an endophyte from a medicinal plant
Tripterigeum wilfordii (Strobel et al., 1999).