https://backend.orbit.dtu.dk/ws/files/101356374/elsevier_8_.pdf

Phylogeny, identification and nomenclature of the genus Aspergillus

Analytical methods for determination of mycotoxins: A review

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. niger 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 information retrieval reasons and there is a taxonomical consensus based on molecular data that the only other common species closely related to A. niger in the Aspergillus series Nigri is A. tubingensis. A. niger, like other filamentous 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. In 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 barrier. A. niger strains produce a series of secondary metabolites, but it is only ochratoxin A that can be regarded as a mycotoxin in the strict sense of the word. Only 3-10% of the strains examined for ochratoxin A production have tested positive under favourable conditions. New and unknown isolates should be checked for ochratoxin A production before they are developed as production organisms. It is concluded, with these restrictions, that A. niger is a safe production organism.

https://link.springer.com/content/pdf/10.1007%2Fs00253-002-1032-6.pdf

On the safety of Aspergillus niger - a review

Aspergillus infections have grown in importance in the last years. However, most of the studies have focused on Aspergillus fumigatus, the most prevalent species in the genus. In certain locales and hospitals, Aspergillus flavus is more common in air than A. fumigatus, for unclear reasons. After A. fumigatus, A. flavus is the second leading cause of invasive aspergillosis and it is the most common cause of superficial infection. Experimental invasive infections in mice show A. flavus to be 100-fold more virulent than A. fumigatus in terms of inoculum required. Particularly common clinical syndromes associated with A. flavus include chronic granulomatous sinusitis, keratitis, cutaneous aspergillosis, wound infections and osteomyelitis following trauma and inoculation. Outbreaks associated with A. flavus appear to be associated with single or closely related strains, in contrast to those associated with A. fumigatus. In addition, A. flavus produces aflatoxins, the most toxic and potent hepatocarcinogenic natural compounds ever characterized. Accurate species identification within Aspergillus flavus complex remains difficult due to overlapping morphological and biochemical characteristics, and much taxonomic and population genetics work is necessary to better understand the species and related species. The flavus complex currently includes 23 species or varieties, including two sexual species, Petromyces alliaceus and P. albertensis. The genome of the highly related Aspergillus oryzae is completed and available; that of A. flavus in the final stages of annotation. Our understanding of A. flavus lags far behind that of A. fumigatus. Studies of the genomics, taxonomy, population genetics, pathogenicity, allergenicity and antifungal susceptibility of A. flavus are all required.

/pdf/aspergillus-flavus-human-pathogen-allergen-and-mycotoxin-17o1fgnzxk.pdf

Aspergillus flavus: human pathogen, allergen and mycotoxin producer.

Aspergillus flavus: human pathogen, allergen and mycotoxin producer: a review

The genus Aspergillus

The Genus Aspergillus

Stalk Formation in Dictyostelium

To determine whether ochratoxin is produced by species of Aspergillus other than Asp. ochraceus, 44 strains representative of the 9 spp. composing the Asp. ochraceus group were grown on both pearled wheat and cracked corn in duplicate shaken flasks at 28°C for 5 days. Rice was a poor substrate for ochratoxin production. Moulded substrates were extracted with acetonitrile-water; partially purified extracts were assayed for ochratoxins by TLC. All positive samples were confirmed by solubility in sodium bicarbonate and preparation of methyl esters. Ochratoxins A and B were found in some strains of Asp. sulphureus, Asp. sclerotiorum, Asp. alliaceus, Asp. melleus, Asp. ochraceus, Asp. ostianus, and Asp. petrakii. No ochratoxin was produced by the one strain of Asp. elegans or any of 6 strains of Asp. auricomus. 5 of 9 strains of Asp. sclerotiorum and 5 of 11 strains of Asp. ochraceus were negative. All 7 strains of Asp. alliaceus were positive, but one was at a very low level. Generally, yields of ochratoxin were higher in wheat than in corn. Occasionally, as much ochratoxin B was produced as A. Highest yields of ochratoxins A and B were obtained from respective strains of Asp. ochraceus NRRL 3174 and NRRL 3519. Some strains of most species of the Asp. ochraceus group produce this mycotoxin as a secondary metabolite.

https://www.jstor.org/stable/info/3757871

Aspergilli as ochratoxin producers.

The research reported in this note was prompted by a chance observation during a study of Clostridium perfringens (Veillon & Zuber) Holland in corn and milled corn products on Sulfide Polymyxin Sulfadiazine (SPS) agar (Difco 1 0845). Plates of this complex medium, allowed to sit on the bench during examination of corn samples, became contaminated with a fungus, later identified as A. flavus, that produced a persistent bright yellow-orange pigment, near Cadmium Yellow 2 (P1. III, Ridgway, 1912), under nonsporulating colonies. Both the pigmentation and lack of sporulation were considered desirable attributes: While the former would permit easy detection, the latter would prevent development of secondary colonies with resultant inaccuracies in counts. Experimentation showed that a simplified medium consisting of 1.5% tryptone, 1.0% yeast extract, 0.05% ferric citrate, and 1.5% agar (Aspergillus differential medium, ADM) could be substituted for SPS without changing the reverse pigmentation or inducing sporulation of the isolate. The ferric ion was found to be essential for pigment production.

Dorothy I. Fennell

Papers

The genus Aspergillus

The Genus Aspergillus

Stalk Formation in Dictyostelium

Aspergilli as ochratoxin producers.

A medium for rapid identification and enumeration of Aspergillus flavus and related organisms.