|Director : PAPIEROK Bernard (email@example.com)|
The Fungi Collection of the Institut Pasteur is in charge of about 2000 strains of fungi (filamentous and yeasts) and Actinomycetes, of which most originated from human lesions. In addition to specific collection activities (cultures, control, distribution, identification), the laboratory carried out investigations on characterization, systematics and ecology of filamentous fungi, especially enthomopathogenic ones. As in 2000, molecular tools were used in order to progress in the knowledge of Entomophthorales from various origins. The study focused on Erynia dipterigena strains originating from Senegal and Guinea. A size polymorphism for the rDNA ITS1-5,8S-ITS2.
The fungi Collection of the Institut Pasteur is in charge of about 2000 strains of fungi (filamentous and yeasts) and Actinomycetes, of which most originated from humain lesions. This outstandingly varied collection, as regards this aspect, includes also strains from environmental origin (air, soil, decaying vegetation, dead insects).
This collection was established thanks to development of medical mycology at the Institut Pasteur. It used to be an integral part of the Mycology unit till the end of 2000. The collection is a distinctive laboratory now and the present activity report is its first specific one.
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, we ensure strains identification. We provide also most of the isolates used in the laboratory work at the annual Institut Pasteur Medical Mycology course.
In association with 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 microorganisms were not yet studied. So, the 2001 research work was dedicated to the material collected in Senegal and Guinea at the end of 2000.
1. Diversity of entomopathogenic fungi in West Africa (Bernard PAPIEROK)
The collection trip in the south-eastern part of Senegal and the north-western part of Guinea (Fouta Djallon) was carried out in collaboration with the Research/Development Federative Programme of the Gambian Basin (leader, Jean Louis DUMAS, French Ministry of Foreign Affairs).
As it was already observed during previous studies in Ivory Coast, the relative importance and diversity of entomopathogenic fungi appeared depending on the altitude and vegetation. Thus, collections were revealed less numerous in the south-eastern part of Senegal than the north-western part of Guinea. As regards Entomophthorales (Zygomycetes), Batkoa and Entomophaga species were found in the two countries (on Homoptera, Lepidoptera, Hymenoptera, Orthoptera), but Erynia dipterigena were found in Diptera populations. Diptera were also found infected by Zoophtora radicans. This is the first report of these two entomophthoralean species in West Africa.
When considering other fungal groups, enthomopathogenic mitosporic fungi were observed in Senegal and Guinea as well (Aschersonia spp., Nomuraea spp., Gibellula spp.), whereas Ascomycetes were found in the latter country only (Cordyceps spp., Torrubiella spp.).
2. Phenotypic and molecular characterization of Entomophthorales isolated from Diptera in Africa (Claire MULOT, Martine KIREDJIAN, Bernard PAPIEROK)
The E.dipterigena material originating from Guniea was studied at the molecular level, together with strains of the same species isolated previously in Congo. According to the results gained in 2000 with European Erynia strains, we considered the rDNA ITS1-5,8S-ITS2 region. The size of the PCR-amplified fragment was shown to be 1100, 1200 and 1400 bp respectively, according to the strains, with a majority of strains with a 1200 bp size (either from Senegal or Guinea). Strains with 1100 bp size originated from the two countries. The 1100 bp size characterized the previously studied European isolates. A 1400 bp size was demonstrated in guinean strains only. Such a size polymorphism for the ITS1-5,8S-ITS2 region was already reported in a few entomophthoralean species.
Analysis of the partial sequencing of this rDNA region (part 3' of RNA 18S and tip 5' of ITS1, and tip of ITS2 and part 5' of RNA 28S respectively) led to distinguish 5 groups among the strains. The two groups with a 1100 or 1200 bp size appeared consistently distinctive. However,strains with a 1200 bp size were divided into 2 or 3 distinctive groups according to the sequence. These differences seemed not related to significant morphological or caryological differences, even if it's an accepted fact that Erynia dipterigena is a morphologically variable species.
|Publications of the unit on Pasteur's references database|
|Office staff||Researchers||Scientific trainees||Other personnel|
PAPIEROK Bernard, Institut Pasteur, firstname.lastname@example.org
KIREDJIAN Martine, Institut Pasteur, email@example.com
COUTANSON Monique, technician IP
PIETFROID Alain, technician IP