Abstract Aspergillus niger is one of the most important microorganisms used in biotechnology. It has been in use already for many decades to produce extracellular (food) enzymes and citric acid. In fact, citric acid and many A. niger enzymes are considered GRAS by the United States Food and Drug Administration. In addition, A. ni- ger is used for biotransformations and waste treatment. In the last two decades, A. niger has been developed as an important transformation host to over-express food enzymes. Being pre-dated by older names, the name A. niger has been conserved for economical and infor- mation retrieval reasons and there is a taxonomical con- sensus based on molecular data that the only other com- mon species closely related to A. niger in the Aspergillus series Nigri is A. tubingensis. A. niger, like other fila- mentous fungi, should be treated carefully to avoid the formation of spore dust. However, compared with other filamentous fungi, it does not stand out as a particular problem concerning allergy or mycopathology. A few medical cases, e.g. lung infections, have been reported, but always in severely immunocompromised patients. I tropical areas, ear infections (otomycosis) do occur due to A. niger invasion of the outer ear canal but this may be caused by mechanical damage of the skin barri A. niger strains produce a series of secondary meta lites, but it is only ochratoxin A that can be regarded as mycotoxin in the strict sense of the word. Only 3–10% of the strains examined for ochratoxin A production hav tested positive under favourable conditions. New and u known isolates should be checked for ochratoxin A pro- duction before they are developed as production or isms. It is concluded, with these restrictions, that A. ni- ger is a safe production organism. Introduction Aspergillus niger has been the subject of research and dustrial use for several decades. It first acquired practi importance in 1919, when its ability to produce citric a id was industrially exploited. Gluconic and fumaric acid have been produced with A. niger, although they are of less economic importance. However, since the 1960 A. niger has become a source of a variety of enzy that are well established as technical aids in fruit cessing, baking, and in the starch and food indust Gene technology has been successfully applied to i prove production processes and to make use of A. niger as an expression system for foreign proteins. The inten research over the past decade has resulted in a range o new processes and products. Ecology Many black Aspergilli have been isolated from all over the world. A. niger is a filamentous fungus growing aer obically on organic matter. In nature, it is found in soil and litter, in compost and on decaying plant mater Reiss (1986) collected data on the influence of tempera ture, water activity and pH on the growth of vario Dr. Schuster (presently retired from Röhm GmbH – Röhm is now AB Enzymes GmbH) prepared the first draft of this manuscript in 1993 on behalf of the AD HOC 5 working group of AMFEP [As- sociation of Manufacturers of Fermentation Enzyme Products, Brussels]; later on, contributions from Dr. Dunn-Coleman and Dr. Frisvad were included. The present manuscript is a revised and updated version prepared by Drs. Frisvad and Van Dijck. E. Schuster Enzyme Technology, Röhm GmbH, Kirschenallee 45, 64293 Darmstadt, Germany N. Dunn-Coleman Genencor International Inc., 925 Page Mill Road, Palo Alto, CA 94304, USA J.C. Frisvad BioCentrum-DTU, Building 221, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark P.W.M. van Dijck ( ✉ ) DSM Food Specialties, Department of Regulatory Affairs, 600–0245, P.O. Box 1, 2600MA, Delft, The Netherlands e-mail: piet.dijck-van@dsm.com Appl Microbiol Biotechnol (2002) 59:426–435 DOI 10.1007/s00253-002-1032-6 M I N I - R E V I E W E. Schuster · N. Dunn-Coleman · J. C. Frisvad P. W. M. van Dijck On the safety of Aspergillus niger – a review Received: 6 March 2002 / Revised: 17 April 2002 / Accepted: 19 April 2002 / Published online: 25 June 2002 © Springer-Verlag 2002