Bacillus subtilis  INDUCES MORPHOLOGICAL CHANGES IN  Fonsecaea pedrosoi IN VITRO  RESULTING IN MORE RESISTANT FUNGAL FORMS  IN VIVO

Machado AP (1, 2) Anzai M (1), Fischman O (2)

(1) Department of Basic Health Sciences, Federal University of Mato Grosso, Cuiabá, Mato Grosso State, Brazil; (2) Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, UNIFESP,  São Paulo, São Paulo State, Brazil.

ABSTRACT: Interactions among microorganisms may be the cause of morphological modifications, particularly in fungal cells. The aim of this work was to examine the changes that occur in cells of the fungus Fonsecaea pedrosoi after co-culturing with Bacillus subtilis in vitro and to explore the results of this interaction in vivo in an experimental murine infection. B. subtilis strain was inoculated into a 15-day pure culture of F. pedrosoi. In vitro, after 48 hours of co-culturing, the fungal cells were roundish. The secretion of fungal dark pigments and production of terminal chlamydoconidia were observed in hyphae after one week. In the in vivo study, two animal groups of 30 BALB/c mice each were employed. One group was inoculated intraperitoneally with hyphal fragments from the co-culture of bacteria and fungi; the other group was infected only with F. pedrosoi hyphae. After seven days of infection, both animal groups developed neutrophilic abscesses. Phagocytosis of bacilli by macrophages occurred after three days. At later periods, generally after 25 days, only roundish cells similar to sclerotic bodies remained in the tissues while hyphae were eliminated by 15 to 20 days. These fungal forms originated mainly from terminal chlamydoconidia. The co-culturing between bacteria and fungus may be a way to rapid obtain resistant fungal forms for host defenses, especially for chromoblastomycosis (CBM) experimental infections.

KEY WORDS: Bacillus subtilis, Fonsecaea pedrosoi, microbial interaction, co-culture, fungal antagonism.

CORRESPONDENCE TO:

ALEXANDRE PAULO MACHADO, Laboratório de Microbiologia, Departamento de Ciências Básicas em Saúde, Faculdade de Ciências Médicas, Universidade Federal de Mato Grosso, av. Fernando Corrêa, s/n, Coxipó, Cuiabá, MT, 78060-900, Brasil. Phone: +55 65 3615 8835. Email: alexandre.paulo@unifesp.br or alepaulo@hotmail.com