title: Lipopeptides from Bacillus subtilis AC7 inhibit adhesion and biofilm formation of Candida albicans on silicone.
abstract: Candida albicans is the major fungus that colonises medical implants, causing device-associated infections with high mortality. Antagonistic bacterial products with interesting biological properties, such as biosurfactants, have recently been considered for biofilm prevention. This study investigated the activity of lipopeptide biosurfactant produced by Bacillus subtilis AC7 (AC7 BS) against adhesion and biofilm formation of C. albicans on medical-grade silicone elastomeric disks (SEDs). Chemical analysis, stability, surface activities of AC7 BS crude extract and physicochemical characterisation of the coated silicone disk surfaces were also carried out. AC7 BS showed a good reduction of water surface tension, low critical micelle concentration, good emulsification activity, thermal resistance and pH stability. Co-incubation with 2 mg ml(-1) AC7 BS significantly reduced adhesion and biofilm formation of three C. albicans strains on SEDs in a range of 67-69 % and of 56-57 %, respectively. On pre-coated SEDs, fungal adhesion and biofilm formation were reduced by 57-62 % and 46-47 %, respectively. Additionally, AC7 BS did not inhibit viability of C. albicans strains in both planktonic and sessile form. Chemical analysis of the crude extract revealed the presence of two families of lipopeptides, principally surfactin and a lower percentage of fengycin. The evaluation of surface wettability indicated that AC7 BS coating of SEDs surface was successful although uneven. AC7 BS significantly prohibits the initial deposition of C. albicans and slows biofilm growth, suggesting a potential role of biosurfactant coatings for preventing fungal infection associated with silicone medical devices.
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro", Largo Donegani 2, 28100, Novara, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Ceresa
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro", Largo Donegani 2, 28100, Novara, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Rinaldi
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Chiono
authors.affiliation: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Carmagnola
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro", Largo Donegani 2, 28100, Novara, Italy.
authors.forename: Gianna
authors.initials: G
authors.lastname: Allegrone
authors.affiliation: Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro", Largo Donegani 2, 28100, Novara, Italy. letizia.fracchia@uniupo.it.
authors.forename: Letizia
authors.identifier: http://orcid.org/0000-0003-3505-1919
authors.initials: L
authors.lastname: Fracchia
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000737:chemistry*; D018441:Biofilms / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development; D055666:Lipopeptides / Q000494:pharmacology*; D012828:Silicones
chemical_list: D000935:Antifungal Agents; D055666:Lipopeptides; D012828:Silicones
keywords: Anti-adhesion; Biofilm; Candida albicans; Coating; Lipopeptide biosurfactant; Medical device