Alkylamidobetaines Induced Changes in Multidrug-Resistant, Biofilming Candida glabrata - Analysis of Oxidative Stress and Cellular Proteome

Antibiofilm strategies targeting Candida glabrata increasingly focus on membrane-active compounds capable of disrupting biofilm formation and mature biofilm structure. Building on previous work identifying alkylamidobetaine C9 (AAB C9) - [(3-decanoylmethylamino)propyl]dimethylammonium acetate - and β-escin as antibiofilm agents against C. glabrata, this study examined the biochemical and physiological basis of their efficacy in a reference strain (ATCC 90030) and a clinical isolate (2586). Oxidative stress was assessed microscopically after two hours of exposure, and proteome changes were quantified after six hours, for each compound alone and in combination. C. glabrata cells retained membrane integrity under all treatment conditions, indicating that antibiofilm activity does not stem from membrane lysis. β-Escin induced the strongest mitochondrial and superoxide ROS response in the reference strain, whereas the AAB C9–β-escin combination was most effective in the clinical isolate, revealing strain-dependent sensitivity. Proteomic analysis identified altered abundance of proteins involved in protein quality control (FES1), transcriptional regulation (SPT4), DNA replication initiation (SLD3), and glucose transport (HXT10). Notably, β-escin reduced abundance of the virulence-associated β-mannosyltransferase, and AAB C9 reduced the multidrug transporter TPO1_1, linked to azole and antimicrobial peptide resistance. These findings suggest that AAB C9 and β-escin act through selective, strain-dependent remodeling of membrane-associated proteins coupled with oxidative and proteostatic stress, supporting their potential as antibiofilm and antifungal agents against C. glabrata.