Dry rot species of fungi cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin. The term "dry rot" is somewhat misleading, as both species of fungi "Serpula lacrymans" and "Meruliporia incrassata" require an elevated moisture content to initiate an attack on timber (28–30%). Once established, the fungi can remain active in timber with a moisture content of more than 20%. At relative humidities below 86 percent, growth of "Serpula lacrymans" is inhibited, but it can stay dormant at relative humidities down to 76 percent. These relative humidities correspond to equilibrium moisture contents
Atromentin 4-HPP to observe the formation of atromentin. This was followed by characterization of the enzyme GreA in "Suillus grevillei", six (InvA1-6, of which InvA1, 2 and 5 were functional) in "Paxillus involutus", and NPS3 from "Serpula lacrymans". In addition, there is another adjacent and conserved gene encoding for an alcohol dehydrogenase/oxidoreductase whose function is unclear. In most cases the clustered biosynthetic genes are found orthologous in basidiomycetes. A common promoter motif was found shared between the atromentin synthetase and aminotransferase of 23 different atromentin-producing basidiomycetes that was in almost all cases absent from the alcohol dehydrogenase, indicating co-regulation of the