Aspergillus flavus genetic structure at a turkey farm

Background The ubiquitous environmental fungus Aspergillus flavus is also a life‐threatening avian pathogen. Objectives This study aimed to assess the genetic diversity and population structure of A. flavus isolated from turkey lung biopsy or environmental samples collected in a poultry farm. Methods A. flavus isolates were identified using both morphological and ITS sequence features. Multilocus microsatellite genotyping was performed by using a panel of six microsatellite markers. Population genetic indices were computed using FSTAT and STRUCTURE. A minimum‐spanning tree (MST) and UPGMA dendrogram were drawn using BioNumerics and NTSYS‐PC, respectively. Results The 63 environmental (air, surfaces, eggshells and food) A. flavus isolates clustered in 36 genotypes (genotypic diversity = 0.57), and the 19 turkey lung biopsies isolates clustered in 17 genotypes (genotypic diversity = 0.89). The genetic structure of environmental and avian A. flavus populations were clearly differentiated, according to both F‐statistics and Bayesian model‐based analysis’ results. The Bayesian approach indicated gene flow between both A. flavus populations. The MST illustrated the genetic structure of this A. flavus population split in nine clusters, including six singletons. Conclusions Our results highlight the distinct genetic structure of environmental and avian A. flavus populations, indicative of a genome‐based adaptation of isolates involved in avian aspergillosis. Aspergillus flavus is the chief avian aspergillosis agent in the Sfax region of Tunisia. In this multilocus microsatellite genotyping population genetic study, we showed a predominant clonal reproduction mode, and a migration flow between A. flavus isolates collected in the same commercial poultry farm, and the overall distinct genetic structure, with the presence of gene flow, between avian and environmental A. flavus populations. Our findings indicate that turkeys’ aspergillosis resulted of the spreading of a population, rather than of a small set of genotypes, of environmental A. flavus isolates.