The fungus CI-4A was discovered as an endophyte associated with Persea indica in the laurisilva forest of the Canary Islands. It was identified as Hypoxylon sp. as the perfect stage and Nodulosporium sp. as the imperfect stage (SEM photograph of the imperfect stage). The organism can easily be grown on normal laboratory media. However, most interestingly it is also capable of growing on plant biomass. During growth, the organism makes and releases a number of volatile compounds that are of interest since they have potential as fuels. Fuel–like compounds being made by fungi have been dubbed Mycodiesel™.
The fungus makes the compound cineole along with a number of other cyclohexanes (colorless, flammable liquids found in petroleum crude oil that represent compounds with enormous fuel potential). Cineole is of special interest since it has been shown that it can be added to gasoline at a ratio of 8 parts cineole to 1 part of gasoline, ending up with a final octane rating of 95. Cineole, having an odor of a eucalyptus tree, had in fact been previously known only from higher plant sources. Now it seems that it can be made by fermentation. Its placement in the market will have to await fungal strain improvement, and other developmental factors needed to optimize its production. In addition, engine testing will be necessary to learn if modifications in design will be needed to handle the new Mycodiesels.
Finally, a close examination of the volatile organic products of a number of endophytic fungi reveals that these products and their related substances are the principal ingredients of regular diesel fuel. Such compounds are the cyclic and straight-chained hydrocarbons such as octane, heptane and cyclohexane followed by the benzene and naphthalene derivatives.
It turns out that many of the compounds found in diesel fuel are either directly found as fungal products or other products that are closely related. This along with a number of other arguments suggests that some or all of the world's crude oil may have originated from microbial sources. Therefore, as the vast amount of organic matter in the world began the processes of decay, the reduced organic products resulting from these processes may have been trapped in the numerous shales of the Earth. It is from these sources that crude oil is mostly recovered.
Genome Reference(s)
Wu W, Davis RW, Tran-Gyamfi MB, Kuo A, LaButti K, Mihaltcheva S, Hundley H, Chovatia M, Lindquist E, Barry K, Grigoriev IV, Henrissat B, Gladden JM
Characterization of four endophytic fungi as potential consolidated bioprocessing hosts for conversion of lignocellulose into advanced biofuels.
Appl Microbiol Biotechnol. 2017 Mar;101(6):2603-2618. doi: 10.1007/s00253-017-8091-1