IMPEDIMETRIC CLAVMO PEPTIDE-BASED SENSOR DIFFERENTIATES PLOIDY OF CANDIDA SPECIES

Yeast biotechnologies are a cornerstone to modern lifestyle in all spheres of society, as their products are essential for the economy and industrial activities. The life cycle of many yeasts such as Candida alternates between diplophase and haplophase. Both ploidies can exist as stable cultures; however, it has been shown that wild haploid yeast efficiently cross in poor environments, whereas wild diploid species hybridize predominantly in rich nutrient surroundings. Some Candida species have had their ploidy engineered to produce various important biomolecules useful to the detergent, food, pharmaceutical and other industries. Several works show that MALDI-TOF MS has become an ideal platform for ploidy analysis. Recent reports have shown that antimicrobial peptides (AMP) present enhanced hydrophobic interaction towards cell membranes. In this work, the authors explored a modified AMP named Clavanin A (CLAVMO) as an unprecedented bioreceptor capable of differentiating the molecular composition of the cell wall of Candida spp. A thin film of poly(3-thiophene acetic acid) (PTAA) was electropolymerized to avail the covalent immobilization of amino-functionalized titanium dioxide nanoparticles (TiO2NPs) whose electrochemical properties are excellent to provide a discernable redox response. Electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) were used to characterize the biosensor assembly and the biorecognition process. Additionally, MALDI-TOF was employed to confirm ploidy of Candida strains used in this work. Our results suggest that TiO2NPs_CLAVMO biosensor is a suitable biological probe that can be used to detect and differentiate Candida species based on their ploidy. For instance, C. Albicans and C. tropicalis, which are close related species known for being diploid presented higher impedimetric response than haploid species C.krusei and C. glabrata. The proposed biosensor stands out as a useful alternative for highly sensitive differentiation of Candida yeast cells, without the intricacies of MALDI-TOF sample preparation. The biodetection event and its electrochemical evaluation took less than 20 min to perform. The platform showed stability for over a week, a linear detection range between 101-106 CFU mL-1 and limits of detection (LODs) between 2 and 3 CFU mL-1.