Bacillus subtilis induces morphological changes in Fonsecaea pedrosoi in vitro resulting in more resistant fungal forms in vivo

Abstract

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 in vitro co-culturing with Bacillus subtilis 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 at 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 fungi may constitute a mechanism to rapidly 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. In a preliminary study, we isolated an environmental gram-positive bacterium from Brazilian soil that antagonizes several fungi, including some dematiaceous species (23). Herein, we studied the interactions between this bacterium and a clinical strain of F. pedrosoi in two manners: firstly, we examined the in vitro changes in fungal cells after co-culturing with bacillus, and secondly, we explored the in vivo significance of this interaction. Original PaPer MATERIALS AND METHODS AnimalsTwo groups of 30 male BALB/c mice each weighing about 23 g (6 to 8-week-old), were used throughout this study. The specific-pathogenfree animals were purchased from CEDEME/ UNIFESP (Brazil). The protocol used was approved by the UNIFESP Ethics Committee under project number 0808/05. MicroorganismsF. pedrosoi strain (EPM -380/03) was isolated from a patient with CBM examined in the Dermatology Outpatient Department, UNIFESP, in 2003. It was cultivated on Sabouraud dextrose agar (SDA -Difco Laboratories, USA) supplemented with 80 mg/L gentamycin at a temperature of 28°C, with periodic transfers at 15-day intervals into a new SDA medium containing antibiotics. An environmental bacillus isolated from random soil samples collected from the campus of the Federal University of Mato Grosso (Cuiabá, Mato Grosso state, Brazil) was used in this study; as in previous co-culture assays, it was able to inhibit the growth of some phytopathogenic fungi and to induce the release of dark pigment by dematiaceous molds. ...

Phyllosphere Fungal Communities of Plum and Antifungal Activity of Indigenous Phenazine-Producing Pseudomonas synxantha Against Monilinia laxa

“…Since no contacts between the bacterial and fungal colonies were established, melanization of the cell wall was presumably caused by a diffusible and soluble bacterial product other than that extracted by benzene. Similar results, with either diffusion of melanin on agar plates and/or melanization of fungal cells, were obtained by several authors: Machado et al (2010a, b) in co-cultures of Aspergillus niger , A. alternata and Fonsecaea pedrosoi with Bacillus subtilis ; and Frases et al (2007) after co-culturing Cryptococcus neoformans with Klebsiella aerogenes. The observed melanization of the M. laxa hyphal cell wall is a typical stress response to adverse environmental conditions, known to be induced by several factors: microbial antagonism (as a way to increase antifungal resistance), host defense mechanisms, predation by amoebae, extreme temperatures, UV radiation, hydrolytic enzymes, oxidative radicals, metal toxicity (Fogarty and Tobin, 1996; Henson et al, 1999; Nosanchuk and Casadevall, 2003).…”

Antagonistic effect of the newly isolated PGPR Bacillus spp. on Fusarium oxysporum

“…that can damage the fungal cellular walls. Bacterial exo-chitinases and glucanases may have an important antagonist role against fungi (Machado et al 2010).…”

Spectroscopic Characterization, Thermogravimetry and Biological Studies of Ru(III), Pt(IV), Au(III) Complexes with Sulfamethoxazole Drug Ligand

“…Adamo et al in [31] compared the activity of SMX and the complexes of (Co(II)) and Cu(II) against S. aureus and E. coli; they found that the hazard of the activity was improved. The improved performance of the complexes is due to chelation, with the increase in lipophilic properties ultimately decreasing the polarity of the metal atom, allowing it to permeate through the bacterial membrane's lipid layers [32,33]. As a result, [Co(C 10 H 11 N 3 O 3 S)] and [Cu(C 10 H 11 N 3 O 3 S)] could be used as lead compounds for developing antibiotics against the bacteria strains studied (S. aureus and E. coli) [31].…”

“…The biological features of sulfamethoxazole complexes with Au(III), Cd(II), Ni(II), and Zn(II) have been investigated in many papers [29][30][31][32][33][34][35][36][37][38][39][40]. It is worth noting that sulfamethoxazole Au(I) and Ag(I) compounds were earlier synthesized and described using X-ray diffraction, with the influence of these complexes on Gram-negative and Gram-positive microorganisms being examined [30].…”