New ochratoxin A or sclerotium producing species in Aspergillus section Nigri

Aspergillus section Nigri includes some of the most important species for biotechnology and its species are of widespread occurrence. During our surveys of various food products and tropical soil we isolated several aspergilli belonging to section Nigri. In this paper, four new sclerotium and/or ochratoxin A producing species belonging to this section are proposed. In addition, based on a polyphasic approach using traditional characters, extrolites and β-tubulin sequencing, a provisional revision and synoptic key of section Nigri is proposed. Aspergillus costaricaensis was isolated from soil in Costa Rica and produces large pink to greyish brown sclerotia. Aspergillus lacticoffeatus was found on coffee beans in Venezuela and Indonesia, and is an effective producer of ochratoxin A. Aspergillus piperis was isolated from black ground pepper and produces large yellow to pink brown sclerotia. Aspergillus sclerotioniger was isolated from a green coffee bean and produces large yellow to red brown sclerotia and abundant ochratoxin A. The species A. homomorphus is validated. The ochratoxin A producing black aspergilli are revised. Fifteen species are provisionally accepted in Aspergillus section Nigri, four of these produce ochratoxin A. Ochratoxin A producing species of section Nigri occurring on grapes, raisins and in wine include A. carbonarius and to a lesser extent A. niger. Four species recovered from coffee, viz. A. carbonarius, A. niger, A. lacticoffeatus and A. sclerotioniger, all produce ochratoxin A, but other species of Nigri also occur on this substrate, including A. japonicus and A. tubingensis. The 10 species not producing ochratoxin A are especially interesting for biotechnological exploration, as many other extrolites are produced by these species. Taxonomic novelties: Aspergillus costaricaensis Samson & Frisvad sp. nov., Aspergillus homomorphus Frisvad & Samson sp. nov., Aspergillus lacticoffeatus Samson & Frisvad sp. nov., Aspergillus piperis Samson & Frisvad sp. nov., Aspergillus sclerotioniger Steiman, Guiraud, Sage & Seigle-Mur. ex Samson & Frisvad sp. nov.