Structural and Biochemical Characterization of Candida Associated Polymicrobial Biofilms and their Control

Abstract

Candida albicans and Escherichia coli, are commensals of the gastrointestinal and gastrourinary tract. Both the strains adhere to biotic and abiotic surfaces forming biofilm which is encased within a matrix of polysaccharides. C. albicans mostly exists as a complex polymicrobial community along with Staphylococcus, Streptococcus, Pseudomonas, Escherichia coli etc and showcases a synergistic or an antagonistic behaviour. Biofilm formers develop resistance to host immune responses and treatment with conventional antimicrobials. Biofilm is one of the crucial factors for virulence in C. albicans, E. coli and their coculture on hospital equipment. In our study, individual as well as polymicrobial, high biofilm forming multidrug resistant (MDR) local clinical isolate of C. albicans from a case of invasive candidiasis and Ampicillin resistant standard strain of bacterial culture E. coli ATCC 39936, identified by biofilm tube test and point inoculation were induced on polystyrene substratum. In-vitro biofilm studies were carried out in a 96 well polystyrene microtiter plate in standard Trypticase Soya Broth (TSB) media in the presence and absence of Foetal Bovine Serum (FBS) to study the effect of FBS on growth and biofilm formation by the individual cultures and their co-culture. Preliminary screening of media components mainly the carbon and nitrogen sources using One Variable at a Time (OVAT) followed by media optimization using Central Composite Design (CCD) based Response Surface Methodology (RSM) models for growth and biofilm formation in TSB modified media (TSBM) were carried out. Sucrose and peptone with significant p value (lt0.05) along with pH which also plays a crucial role in influencing growth and biofilm formation were chosen for Central Composite Design (CCD). The response was measured by CV output. The model was validated at critical parameters by CV assay. Biofilm was quantified by growth OD, CV and MTT assays in the presence and absence of FBS in TSBM. The results of growth OD and CV assay in TSBM.