Phylogenomics and gene selection in Aspergillus welwitschiae: Possible implications in the pathogenicity in Agave sisalana.

Aspergillus welwitschiae causes bole rot disease in sisal (Agave sisalana and related species) which affects the production of natural fibers in Brazil, the main worldwide producer of sisal fibers. This fungus is a saprotroph with a broad host range. Previous research established A. welwitschiae as the only causative agent of bole rot in the field, but little is known about the evolution of this species and its strains. In this work, we performed a comparative genomics analysis of 40 Aspergillus strains. We show the conflicting molecular identity of this species, with one sisal-infecting strain sharing its last common ancestor with Aspergillus niger, having diverged only 833 thousand years ago. Furthermore, our analysis of positive selection reveals sites under selection in genes coding for siderophore transporters, Sodium­calcium exchangers, and Phosphatidylethanolamine-binding proteins (PEBPs). Herein, we discuss the possible impacts of these gene functions on the pathogenicity in sisal.

Identification of Listeria monocytogenes in cattle meat using biochemical methods and amplification of the hemolysin gene.

In Brazil and in other countries of the world, studies have been conducted to identify Listeria monocytogenes in cattle meat that is preferably consumed undercooked and, when marketed without meeting strict phytosanitary requirements, may cause outbreaks of listeriosis. In the such, foodborne outbreaks, the methods used for the detection of the pathogen and the efficiency associated with them are crucial for the proper assessment. In this study, we used the techniques biochemical and molecular for identification of the L. monocytogenes isolated from 30 samples of the fresh beef, marketed in ten butchers' shop of the free-fair from a municipality from the Bahia, Brazil. The results obtained from biochemical tests (catalase, motility, ß-hemolysis and carbohydrate fermentation), as well as PCR analysis for the hly gene (hemolysin production is an important factor in the pathogenesis of listeriosis) revealed that 50% of butchers shops presented bovine meat contaminated with bacteria of the Listeria sp. and confirmed that 54.16% of the analyzed meat samples were positive for L. monocytogenes. This study highlights the importance of microbiological surveillance in free-fair to minimize the exposure of consumers to this foodborne pathogen.

Putting the Mess in Order: Aspergillus welwitschiae (and Not A. niger) Is the Etiological Agent of Sisal Bole Rot Disease in Brazil.

Approximately 75% of the worldwide production of hard natural fibers originates from sisal, an industrial crop from arid and semiarid tropical regions. Brazil is the world's largest producer of sisal fiber, accounting for more than 40% of the worldwide production, and sisal bole rot disease has been the main phytosanitary problem of this crop. All previous studies reporting Aspergillus niger as the causal agent of the disease were based on the morphological features of fungal isolates from infected plant tissues in pure cultures. Black aspergilli are one of the most complex and difficult groups to classify and identify. Therefore, we performed an integrative analysis of this disease based on the isolation of black aspergilli from the endospheres and soils in the root zones of symptomatic adult plants, in vivo pathogenicity tests, histopathology of symptomatic plants, and molecular phylogeny and worldwide genetic variability of the causal agent. All sisal isolates were pathogenic and unequivocally produced symptoms of bole rot disease in healthy plants. In all tree-based phylogenetic methods used, a monophyletic group formed by A. welwitschiae along with all sisal isolates was retrieved. Ten A. welwitschiae haplotypes have been identified in the world, and three occur in the largest sisal-producing area. Most of the isolates are from a unique haplotype, present in only the sisal-producing region. A. welwitschiae destroyed parenchymatic and vascular cylinder cells and induced the necrosis of internal stem tissues. Therefore, sisal bole disease is probably the consequence of a saprotrophic fungus that opportunistically invades sisal plants and behaves as a typical necrotrophic pathogen.