Abstract
Candida albicans is a significant cause of morbidity and mortality in immunocompromised patients worldwide. Biofilm formation by Candida species is a significant virulence factor for disease pathogenesis. Keeping in view the importance of Streptomyces' metabolites, the present study was initiated during the bioprospecting programme of Egyptian Streptomyces carried by the authors since 2013. Native Streptomyces isolates were recovered from soil samples collected from different governorates. Antifungal activity of forty isolates of Streptomyces were performed against planktonic (free cells) of C. albicans ATCC 10231 and resistant clinical Candida isolates. Streptomyces isolates showed high inhibition activity against free cells of Candida were further assayed against biofilm of C. albicans reference strain. The most active Streptomyces sp. (no.6) was identified phenotypically, biochemically and by using 16S rRNA. The 16S rRNA sequences obtained were compared with those deposited in the GenBank Database and registered with accession number KM052378 as S. toxytricini Fz94. Screening of S. toxytricini Fz94 extract capability in prevention and destruction of C. albicans reference strain biolfilm was assessed by resazurin dye adopted technique. In the pre-exposure scheme, the lowest concentration of 5 gL-1 showed biofilm viability inhibition of 92% after 120 min, while Ketoconazole® gave 90 % inhibition at concentration of 2 gL-1. In post exposure, the concentration of S. toxytricini Fz94 extract 7gL-1 caused 82 % inhibition of biofilms viability after 120 min, while Ketoconazole did not show any destruction capability. The cytotoxicity of S. toxytricini Fz94 crude extract results showed that it was nontoxic at 10 gL-1. S. toxytricini Fz94 is maintained in the Fungarium of Arab Society for Fungal Conservation (ASFC) with accession number FSCU-2017-1110.
Highlights
Microorganisms growing in a biofilm are associated with chronic and recurrent human infections (Sutherland 2001)
Antifungal activity of forty isolates of Streptomyces were performed against planktonic of C. albicans American Type Culture Collection (ATCC) 10231 and resistant clinical Candida isolates
Isolation of Streptomyces and Screening of antifungal activity against reference strain Out of the forty Streptomyces isolates, Streptomyces sp. 6 isolated from soil of cattle farms in Dakahlya showed strong antifungal activity was selected for identification
Summary
Microorganisms growing in a biofilm are associated with chronic and recurrent human infections (Sutherland 2001). Candida albicans is an important nosocomial pathogen in immunocompromised patients that has a high morbidity and mortality rate (Wisplinghoff et al, 2004, Mensa et al, 2008,). This is due to many of these C. albicans are implant-associated infections, owing in part to its greater capacity to form biofilms that are found on the surfaces of devices including central venous catheters, catheters, prosthetic heart valves, endotracheal tubes, pacemakers and joint replacements that cause bloodstream infection (Douglas, 2002, Chandra et al, 2005, Sardi et al, 2013)
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