Introduction - Biofilm - formation and fungal filamentation are well - recognized virulence factors in Candida pathogenesis, helping the fungus to invade host tissues and promoting its persistence. Modern medicine, characterized by a wide use of biomedical devices, offers new niches for opportunistic fungi able to form biofilm communities. Conventional anti fungal drugs have been demonstrated to be ineffective against biofilms, and alternative strategies and/or drug targets are needed to overcome biofilm - dependent resistance. Recently, some Bacillus amyloliquefaciens strains were reported to have probiotic ac tivity, to be effective for the biocontrol of multiple plant diseases caused by soil - borne fungal pathogens, and to possess mycotoxin degrading ability. In this study, we evaluated the activity of secondary metabolites produced by B. amyloliquefaciens on C andida albicans biofilm. Materials and Methods – C. albicans SC5314, a strong biofilm producer, was used in this study. Bacterial supernatants were obtained by centrifuging 48 - and 72h - old B. amyloliquefaciens ( Ba ) , strain TITI , broth cultures. Biofilm f ormation was induced by sub - culturing C. albicans in a defined medium in 96 - well plate, for total biomass measurement by crystal violet staining, and on 18 - mm - diameter round coverslips, for confocal laser - scanning microscope (CLSM) analysis. Gene expressio n of hyphal wall protein 1 ( HWP1 ) and agglutinin - like sequence 3 (ALS - 3), known to be relevant for C. albicans filamentation and biofilm - formation, was investigated by real - time PCR. Results - We observed a dramatic inhibition of C. albicans ability to adhere to polystyrene surface by both 48 - and 72h - old Ba supernatants. Moreover, Ba supernatants applied to 24 - h preformed biofilms resulted in the detachment of most cells from the wells. CLSM analysis with calcofluor white staining, targeting fungal chitin, showed alterations in morphology of the growing yeast that resulted in stubby hyphae unable to express typical thigmotrophic features. HWP - 1 and ALS - 3 were downregulated in the presence of Ba supernatant. Discussion and Conclusions - Bacill us species are good producers of antimicrobial substances such as peptide and lipopeptide antibiotics, and bacteriocins that have become a highly effective alternative to traditional fungicides against environmental molds. Ba cyclic lipopeptides seem to be long to the surfactin, iturin and fengycin families that act as biosurfactants, perturbating fungal membranes. Our data demonstrate that such compounds could be also effective against medically relevant yeasts and could have potential uses in biotechnology and biopharmaceutical applications.

Antifungal activity of Bacillus amyloliquefaciens supernatants against Candida albicans biofilm / G. Bassanini, F. Borgo, E. Ottaviano, G. Morace, E. Borghi. ((Intervento presentato al 46. convegno Congresso Nazionale della Società Italiana di Microbiologia tenutosi a Palermo nel 2018.

Antifungal activity of Bacillus amyloliquefaciens supernatants against Candida albicans biofilm

G. Bassanini;F. Borgo;E. Ottaviano;G. Morace;E. Borghi
2018-09-27

Abstract

Introduction - Biofilm - formation and fungal filamentation are well - recognized virulence factors in Candida pathogenesis, helping the fungus to invade host tissues and promoting its persistence. Modern medicine, characterized by a wide use of biomedical devices, offers new niches for opportunistic fungi able to form biofilm communities. Conventional anti fungal drugs have been demonstrated to be ineffective against biofilms, and alternative strategies and/or drug targets are needed to overcome biofilm - dependent resistance. Recently, some Bacillus amyloliquefaciens strains were reported to have probiotic ac tivity, to be effective for the biocontrol of multiple plant diseases caused by soil - borne fungal pathogens, and to possess mycotoxin degrading ability. In this study, we evaluated the activity of secondary metabolites produced by B. amyloliquefaciens on C andida albicans biofilm. Materials and Methods – C. albicans SC5314, a strong biofilm producer, was used in this study. Bacterial supernatants were obtained by centrifuging 48 - and 72h - old B. amyloliquefaciens ( Ba ) , strain TITI , broth cultures. Biofilm f ormation was induced by sub - culturing C. albicans in a defined medium in 96 - well plate, for total biomass measurement by crystal violet staining, and on 18 - mm - diameter round coverslips, for confocal laser - scanning microscope (CLSM) analysis. Gene expressio n of hyphal wall protein 1 ( HWP1 ) and agglutinin - like sequence 3 (ALS - 3), known to be relevant for C. albicans filamentation and biofilm - formation, was investigated by real - time PCR. Results - We observed a dramatic inhibition of C. albicans ability to adhere to polystyrene surface by both 48 - and 72h - old Ba supernatants. Moreover, Ba supernatants applied to 24 - h preformed biofilms resulted in the detachment of most cells from the wells. CLSM analysis with calcofluor white staining, targeting fungal chitin, showed alterations in morphology of the growing yeast that resulted in stubby hyphae unable to express typical thigmotrophic features. HWP - 1 and ALS - 3 were downregulated in the presence of Ba supernatant. Discussion and Conclusions - Bacill us species are good producers of antimicrobial substances such as peptide and lipopeptide antibiotics, and bacteriocins that have become a highly effective alternative to traditional fungicides against environmental molds. Ba cyclic lipopeptides seem to be long to the surfactin, iturin and fengycin families that act as biosurfactants, perturbating fungal membranes. Our data demonstrate that such compounds could be also effective against medically relevant yeasts and could have potential uses in biotechnology and biopharmaceutical applications.
Settore MED/07 - Microbiologia e Microbiologia Clinica
Federation of European Microbiological Societies
European Society of Clinical Microbiology and Infectious Diseases
Antifungal activity of Bacillus amyloliquefaciens supernatants against Candida albicans biofilm / G. Bassanini, F. Borgo, E. Ottaviano, G. Morace, E. Borghi. ((Intervento presentato al 46. convegno Congresso Nazionale della Società Italiana di Microbiologia tenutosi a Palermo nel 2018.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/609678
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