Wednesday, 11 July 2012

Nine New Aspergillus Species Identified

Aspergillus and Penicillium species
It turns out that what we were calling species Aspergillus versicolor is in fact a collection of very closely related but distinct species. A recent paper describes the molecular techniques that were used to define the new species. The nine new species names are Aspergillus austroafricanus, A. creber, A. , cvjetkovicii, A. fructus, A. jensenii, A. puulaauensis, A. subversicolor, A. tennesseensis and A. venenatus, based on differences in their gene sequences. This collection of species will now be referred to as Aspergillus section Versicolores (note the capital V!).

It is probably correct to state that this will not be the last time we define new species from what we currently refer to as a single species as the original specification of fungal species were based on microscopic examination of what the fungus looked like when growing under standard conditions (often more than one set of standard conditions) - a largely artificial classification when the difference in appearance can be small. 

Once we start comparing at the precise features of the DNA of strains originally identified as belonging to one species we are already working with much more information with which to classify the fungi, the main difficulty now may be deciding which genetic differences to use to define species as there may be many.

This is a steadily ongoing process and the numbers of species are steadily growing (currently standing at 955) - in 2001 Aspergillus section Flavi was designed to contain several of the species Aspergillus flavus and there are several more groupings. There have been several attempts to rationalise the taxonomy of Aspergillus in the past and such is the complexity it is still a subject for debate and attempts to set out commonly accepted rules to define a species - see the Polyphasic approach described at a recent Advances Against Aspergillosis Conference in 2008.

For the most recent information on Aspergillus species refer to http://www.mycobank.org/

Also see http://www.aspergilluspenicillium.org/ as it continues to develop

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