Microscopy in mycological research with especial reference to ultrastructures and biofilm studies

Microscopy is the only technique whereby fungal morphology and its cellular structures can be studied. Our understanding of physiology, intracellular and surface structures of fungi are dependent on microscopic techniques. These techniques involved use of classical light microscopes and electron microscopy. However, advancement of microscopic techniques such as fluorescent microcopy, confocal laser scanning microscopy, atomic force microscopy and others involving integration of automated computer monitoring have aided significantly to the mycological research especially structural alterations and biofilm studies. Growing awareness of heterogeneity in cells of microbial populations has emphasized the importance of advanced microscopy for visualization and understanding of the mechanisms underlying cell-to-cell variation. The main role of these techniques is in examining biological specimens such as: (i) visualizing the microbial cell surface layers and ultrastructures (ii) monitoring conformational changes of individual membrane proteins (iii) examining the morphology of biofilms especially exopolysaccahrides matrix containing proteins, carbohydrates and nucleic acids, with the capability of fully revealing them in three dimension (iv) studying the nanoscale structure of living microbial cells (v) probing the local mechanical properties of cell surface layers of single cells. A large number of critical molecular and cellular events occur at the cell surface of fungi; such as cell adhesion, secretion, cytoskeletal interactions, membrane dynamics and cell wall deposition. Investigating such phenomena is easily approached by selective visualization of surface regions of fungal and other eukaryotic cell systems using advanced microscopical techniques. The paper emphasizes the recent applications of various microscopic techniques to study cellular morphology and its alteration under stress conditions and biofilm monitoring in fungi.