Open AccessMetal Ions May Suppress or Enhance Cellular Differentiation in Candida albicans and Candida tropicalis Biofilms
Author(s) -
Joe J. Harrison,
Howard Ceri,
Jérôme Yerly,
Maryam Rabiei,
Yaoping Hu,
Robert J. Martinuzzi,
Raymond J. Turner
Publication year - 2007
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.02711-06
Subject(s) - biofilm , candida tropicalis , candida albicans , microbiology and biotechnology , hypha , yeast , biology , metal ions in aqueous solution , corpus albicans , metal , cell wall , chemistry , bacteria , biochemistry , genetics , organic chemistry
Candida albicans andCandida tropicalis are polymorphic fungi that develop antimicrobial-resistant biofilm communities that are characterized by multiple cell morphotypes. This study investigated cell type interconversion and drug and metal resistance as well as community organization in biofilms of these microorganisms that were exposed to metal ions. To study this,Candida biofilms were grown either in microtiter plates containing gradient arrays of metal ions or in the Calgary Biofilm Device for high-throughput susceptibility testing. Biofilm formation and antifungal resistance were evaluated by viable cell counts, tetrazolium salt reduction, light microscopy, and confocal laser scanning microscopy in conjunction with three-dimensional visualization. We discovered that subinhibitory concentrations of certain metal ions (CrO4 2− , Co2+ , Cu2+ , Ag+ , Zn2+ , Cd2+ , Hg2+ , Pb2+ , AsO2 − , and SeO3 2− ) caused changes in biofilm structure by blocking or eliciting the transition between yeast and hyphal cell types. Four distinct biofilm community structure types were discerned from these data, which were designated “domed,” “layer cake,” “flat,” and “mycelial.” This study suggests thatCandida biofilm populations may respond to metal ions to form cell-cell and solid-surface-attached assemblages with distinct patterns of cellular differentiation.