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  Director : PAPIEROK Bernard (papierok@pasteur.fr)


  abstract

 

The Fungi Culture Collection of the Insitut Pasteur is in charge of more than 2000 strains of fungi (filamentous fungi and yeasts) and Actinomycetes, most of which originated from human lesions. In addition to specific collection activities (cultures, identity and viability checking, distribution), the laboratory carried out investigations on characterization, systematics and ecology of filamentous fungi, especially Entomophthorales with entomopathogenic potential. In 2002, the comparative sequencing of the rDNA ITS1-5.8S-ITS2 region was used to progress in characterization of strains of Basidiobolus spp. and Conidiobolus spp. isolated from decaying plant material, soil, lesions in mammals or invertebrate cadavers.



  report

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The Fungi Culture Collection of the Insitut Pasteur is in charge of more than 2000 strains of fungi (filamentous fungi and yeasts) and Actinomycetes, most of which originated from human lesions. This outstandingly varied collection, as regards this aspect, includes also strains from environmental origin (air, soil, decaying plant material, dead invertebrates, mostly insects).

The basic activity of the laboratory is to keep strains in pure culture and to distribute them to the interested research laboratories, as well as to industrial and pharmaceutical ones and to education establishments. Furthermore, the Fungi Culture Collection ensures strain identification. It provides also most of the isolates used in the laboratory work at the annual Institut Pasteur Medical Mycology course, and is involved directly in the Institut Pasteur Biological Ressources Centre project.

In association with these specifically speaking collection activities, the laboratory carried out investigations on characterization, systematics and ecology of filamentous fungi. Owing to the experience of the involved people, these research activities focus on entomophthoralean species (Zygomycetes) with entomopathogenic potential. In 2002, the laboratory gave greater importance to the sequencing of the whole rDNA ITS1-5.8S-ITS2 region in strains of several species belonging to the Basidiobolus and Conidiobolus genera, and originated from decaying plant material, lesions in mammals or invertebrate cadavers.

Within Entomophthorales indeed, these two genera are distinguished by the fact that they are mostly saprophytic, but several species are more or less regularly isolated from lesions in humans and some other mammals, or from invertebrate cadavers. Furthermore, a few Conidiobolus species are only known as naturally occurring entomopathogens.

Molecular characterization fo strains of Basidiobolus spp. (Delphine DARDALHON, Martine KIREDJIAN, Bernard PAPIEROK)

Whatever the result of the previous phenotypic identification of the strains (Basidiobolus haptosporus, B. meristosporus, B. ranarum) , the size of their rDNA ITS1-5.8S-ITS2 region is about 700 bp. Sequence analysis showed a noteworthy homogeneity, with no significant splitting between strains originated from human lesions, and strains from other origin (soil, insect cadavers or frog faeces).

Molecular characterization fo strains of Conidiobolus spp. (Delphine DARDALHON, Martine KIREDJIAN, Bernard PAPIEROK)

PCR results demonstrated the ITS size polymorphism within the genus Conidiobolus according to species. Size is 750-850 bp in strains of C. coronatus or C. thromboides whereas it is about 900 bp in C. osmodes. In comparison with these three species, which are saprophytic fungi but occasionnally isolated from invertebrate cadavers, the ITS size in entomopathogenic species such as C. obscurus or C. pseudoapiculatus, was showed to range from 1300 to 1700 bp.

The ITS sequences appeared homogenous within the species C. osmodes and C. thromboides, whatever the original substrate (soil, decaying plant material, invertebrate cadavers), and regardless of geographical origin. Similar results were found in the case of C. coronatus, even when including strains isolated from lesions in mammals. These results reinforce conclusions of previous studies carried out in the laboratory, according to which no parasitic specialization seems to occur within this species.

These investigations gave the opportunity to compare the ITS sequences in the type strain of C. thromboides and type strain of "Entomophthora virulenta". The near identity of the two sequences confirmed unequivocally a previous study, which demonstrated the synonymy between these two species, based on morphological, biochemical and pathogenic characters.

Keywords: Entomophthorales, characterization, ITS, Basidiobolus, Conidiobolus, mycology



  publications

puce Publications of the unit on Pasteur's references database


  personnel

  Office staff Researchers Scientific trainees Other personnel
    KIREDJIAN, Martine,mkiredji@pasteur.fr

PAPIEROK, Bernard,papierok@pasteur.fr

DARDALHON, Delphine COUTANSON, Monique, Technician

PIETFROID, Alain, Technician


Activity Reports 2002 - Institut Pasteur
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