John I. Pitt

Fungi and food spoilage

Introduction. The Ecology of Fungal Food Spoilage. Naming and Classifying Fungi. Methods for Isolation, Enumeration and Identification. Primary Keys and Miscellaneous Fungi. Zygomycetes. Penicillium and Related Genera. Aspergillus and Relataed Teleomorphs. Xerophiles. Yeast. Spoilage of Fresh and Perishable Foods. Spoilage of Stored, Processed and Preserved Foods. Media Appendix. Glossary. Index

Integration of modern taxonomic methods for Penicillium and Aspergillus classification

Their Teleomorphs. Methods for Identification of pencillium and aspergillus. Taxonomic and Digital Information on penicillium and aspergillus. Phylogeny and Molecular Taxonomy of penicillium. Classification and Identification of penicillium. Molecular Taxonomy of aspergillus. Taxonomy of aspergillus Section nigri and Section flavi. Pathogenic Aspergilli and Penicillia. The Potential of penicillium and aspergillus in Drug Lead Discovery.

Differentiation of Aspergillus flavus from A. parasiticus and other closely related species

More than 150 isolates of Aspergillus flavus, A. oryzae, A. parasiticus, A. sojae and A. tamarii from collections around the world were examined independently in two laboratories as unknowns, and data assessed to evaluate a wide range of morphological characters for suitability as taxonomic criteria. Mycotoxin production was also assessed. It was concluded that conidial wall texture was the most effective criterion for distinguishing A. flavus and A. parasiticus. A. flavus has a broad interface with VA. oryzae; therefore, a combination of characters was necessary to separate these two species. Mycotoxin production correlated well with morphological speciation. Only A. flavus and A. parasiticus isolates produced B aflatoxins. Very few A. flavus isolates produced G aflatoxins whereas almost all A. parasiticus isolates did. The A. parasiticus isolates never produced cyclopiazonic acid, but some isolates of A. flavus, A. tamarii and A. oryzae did.

Modern concepts in penicillium and aspergillus classification

In our view, the First International Penicillium and Aspergillus Workshop held in Baarn and Amsterdam in May, 1985, was a great success. The assembly in one place of so many specialists in these two genera produced both interesting viewpoints and lively discussions. But more particularly, a remarkable cohesion of ideas emerged, borne primarily of the realisation that taxonomy has passed from the hands of the solitary morphologist. The future of taxonomy lay in collaborative and multidisciplinary studies embracing morphology, physiology and newer methodologies. Penicillium and Aspergillus Workshop was borne logically The Second International from the first, and was held in Baarn on May 8-12, 1989. It was attended by 38 scientists from 16 countries. At this Workshop we have attempted to move further into new methods, especially by bringing together molecular biologists, medical and food mycologists and biochemists as well as more traditional taxonomists. We feel that the meeting contributed greatly to dialogue between taxonomists, and also fundamental and applied mycologists. At the meeting, we became aware that the approach to taxonomy of these genera is now becoming more pragmatic, with an increasing emphasis on consensus, and on stability of names. This is a noteworthy development, which we, as editors, welcome. So many species in Penicillium and Aspergillus are economically important in biotechnology, foods and medicine, and practical, stable taxonomy is of vital importance. These Proceedings comprise 40 papers divided into 9 chapters.

Predicting fungal growth: the effect of water activity on Aspergillus flavus and related species

Growth of four species belonging to Aspergillus Section Flavi (A. flavus, A. oryzae, A. parasiticus and A. nomius) was studied at 30 degrees C at ten water activities (aw) between 0.995 and 0.810 adjusted with equal mixtures of glucose and fructose. Colony diameters were measured at intervals and plotted against time. A flexible growth model describing the change in colony diameter (mm) with respect to time was first fitted to the measured growth data and from the fitted curves the maximum colony growth rates were calculated. These values were then fitted with respect to aw to predict colony growth rates at any aw within the range tested. The optimum aw for each species and time to reach a colony diameter of 3 mm were also calculated.

Phylogenetic analysis of two ribosomal DNA regions indicates multiple independent losses of a sexual Talaromyces state among asexual Penicillium species in subgenus Biverticillium

ABSTRACTNucleotide sequences were obtained from the mitochondrial small subunit ribosomal DNA, and the nuclear ribosomal DNA region containing the internal transcribed spacers and 5.8S ribosomal RN...

Infrageneric Taxa of Aspergillus

The species of Aspergillus fall into distinct clusters, which have been widely accepted. Since Thom and Church (1926), Thom and Raper (1945) and Raper and Fennell (1965), these clusters have been called “groups”, a category without nomenclatural standing. In a few cases “series” were named, which do have a nomenclatural status (when described before 1935 even without a Latin diagnosis), but they do not compete for priority unless at the same rank. For the sake of simplicity in citation, we prefer to introduce new sections rather than new combinations from previous series. In contrast, in Penicillium subgenera and sections were named at the beginning of the century and a complete scheme was formally devised by Pitt (1979).

An appraisal of identification methods for Penicillium species: novel taxonomic criteria based on temperature and water relations.

Examination of media and methods currently used in Penicillium taxonomy led to the conclusion that by using only two media, Czapek yeast autolysate agar and malt extract agar, and by incubating cul...

Important mycotoxins and the fungi which produce them

The assessment of the relationship between species and mycotoxins production has proven to be very difficult. The modern literature is cluttered with examples of species purported to make particular mycotoxins, but where the association is incorrect. In some cases, mycotoxins have even been named based on an erroneous association with a particular species: verruculogen, viridicatumtoxin and rubratoxin come to mind. As time has gone on, and more and more compounds have been described, lists of species-mycotoxin associations have become so large, and the inaccuracies in them so widespread in acceptance, that determining true associations has become very difficult. It does not need to be emphasised how important it is that these associations be known accurately. The possible presence of mycotoxigenic fungi in foods, and rational decisions on the status of foods suspected to contain mycotoxins, are ever present problems in the food industry around the world. In defining mycotoxins, we exclude fungal metabolites which are active against bacteria, protozoa, and lower animals including insects.

Influence of pH on the growth of some toxigenic species of Aspergillus, Penicillium and Fusarium

The effect of pH on the growth rates of 61 isolates belonging to 13 important toxigenic fungi are reported here: four species each of Aspergillus and Fusarium, and five of Penicillium, over the pH range 2 to 11 at 25, 30 and 37 degrees C. Nearly all species studied were able to grow over the entire range examined on a laboratory agar medium. However, in general, Aspergillus species were more tolerant of alkaline pH while Penicillium species appeared to be more tolerant of acidic pH.