In situ localization of cytochrome P-450, the first enzyme involved in aliphatic hydrocarbon degradation in the yeast Candida maltosa

The Extracellular Vesicles Containing Inorganic Polyphosphate of Candida Yeast upon Growth on Hexadecane

The cell wall of Candida yeast grown on presence of hexadecane as a sole carbon source undergoes structural and functional changes including the formation of specific supramolecular complexes-canals. The canals contain specific polysaccharides and enzymes that provide primary oxidization of alkanes. In addition, inorganic polyphosphate (polyP) was identified in Candida maltosa canals. The aim of the work was a comparative study of the features of cell walls and extracellular structures in yeast C. maltosa, C. albicans and C. tropicalis with special attention to inorganic polyphosphates as possible part of these structures when grown on the widely used xenobiotic hexadecane (diesel fuel). Fluorescence microscopy with DAPI has shown an unusual localization of polyP on the cell surface and in the exovesicles in the three yeast species, when growing on hexadecane. Electron-scanning microscopy showed that the exovesicles were associated with the cell wall and also presented in the external environment probably as biofilm components. Treatment of hexadecane-grown cells with purified Ppx1 polyphosphatase led to the release of phosphate into the incubation medium and the disappearance of polyP in vesicles and cell wall observed using microscopic methods. The results indicate the important role of polyP in the formation of extracellular structures in the Candida yeast when consuming hexadecane and are important for the design of xenobiotic destructors based on yeast or mixed cultures.

Changes in cell wall structure and protein set in Candida maltosa grown on hexadecane

The yeast Candida maltosa is a model organism for studying adaptive changes in the structure and function of the cell wall when consuming water-insoluble nutrient sources. The cells of C. maltosa that utilize hydrocarbons contain supramolecular structures, so-called "canals" in the cell wall. Differences in protein profiles of culture liquids and cell wall extracts of C. maltosa grown on glucose and hexadecane were analyzed. Three proteins specific of cells grown on hexadecane were revealed using mass spectrometry: glycosyl hydrolase EPD2 in the culture liquid; a protein belonging to the cytochrome C family in the 0.5 mol/L NaCl extract; and PPIA_CANAL protein known as chaperone, in the 0.1% SDS extract. The possible role of these proteins in cell wall structures responsible for adaptation to hexadecane utilization is discussed.

Transmission electron microscopy of yeast

The challenges of sample preparation can limit a researcher's selection of transmission electron microcopy (TEM) for analysis of yeast. However, with the exception of thin sectioning, preparation of well-fixed and infiltrated samples of yeast cells is achievable by any reasonably equipped laboratory. This review presents a general overview of TEM sample preparation methods and detailed protocols for chemical fixation of yeast for ultrastructural analysis and immunolabeling. For ultrastructural analysis, the most commonly used chemical fixation involves treatment with glutaraldehyde followed by either potassium permanganate or osmium. Prior to osmium postfixation, the cell wall must be enzymatically digested to allow optimal fixation and embedding. Freeze substitution methods continue to provide the highest quality of fixation, but equipment needed for these protocols is not generally available to many labs. The low viscosity of Spurr's resin makes it the resin of choice for ultrastructure studies. Immunoelectron microscopy has enjoyed great success in analysis of yeast molecular organization. For immunoelectron microscopy, glutaraldehyde/formaldehyde-fixed cells are embedded in LR White resin. The thin sections are then treated in much the same way as an immunoblot: following blocking, they are incubated in primary antiserum, washed, and then incubated in gold-labeled secondary antiserum.