Symbiotaphrina kochii (Pezizomycotina
incertae sedis).
Symbiotaphrina is a genus of yeast-like endosymbionts of
beetles that has been implicated in B-vitamin biosynthesis, fatty
acid metabolism, and detoxification of noxious plant compounds by
insects. The fungi are transmitted vertically on the egg
surface at deposition. Neither the fungi nor beetles have
been found in isolation. The fungi have a number of positive
effects on the insect hosts. In particular they produce
enzymes that degrade a wide variety of noxious compounds they use
as carbon sources; these include flavonoids, tannic acid, phenol,
plant meal toxins, certain mycotoxins and insecticides, and
herbicides such as 2,4D, all compounds usually toxic to insects.
The fungal symbionts allow some beetles known as cigarette beetles
to even live in cigarette packs. The fungi also are involved with
utilizing sterols and helping to recycle nitrogen within the fat
bodies of the insect hosts. As such, there is a strong likelihood
that these fungi are capable of unique metabolic activity of
significant interest to DOE.
Symbiotaphrina has long been the subject of taxonomic
confusion. There exists two known species, S. kochii and
S. buchneri, and they were once considered to be members
of the earliest diverging clade of Ascomycota, then
members of the Saccharomycotina, and finally as
Pezizomycotina . Although a member of the
Pezizomycotina, current phylogenetic analyses support the
genus as a unique and enigmatic lineage of the subphylum and
potentially a new class. Sequencing of the S. kochii
genome will therefore inform phylogenetic analyses directed at
unraveling its evolutionary origin and provide an important
phylogenetic and ecological sampling point for understanding the
complex evolutionary history of fungal metabolism.