[WET-MODE SCANNING ELECTRON MICROSCOPY AS AN INSTRUMENT FOR STUDIES OF BIOGEOCHEMICAL PROCESSES OF FUNGAL BIOMINERALS...

The aim of this work was to examine the potential of the use of one of the modern approaches in scanning electron microscopy--the wet mode ESEM to study biogeochemical processes of biominerals formation by micromycetes. The object of the study was microscopic fungus Beauveria caledonica known for its ability to transform metals and minerals. In response to the presence of copper phosphate in the medium, it was observed the abundant formation of copper oxalate crystals in fungal mycelium. Optimal visualization at wet mode was achieved at the sample chamber pressure around 6 torr and relative humidity 85 - 90%. The comparison of the observations obtained using high-vacuum mode and wet mode scanning electron microscopy showed that in their natural state fungal hyphae and mycelial cords are surrounded by thick hydrated mucilaginous sheath which serves as a matrix for biogeochemical processes of secondary minerals formation and growth. The wet mode and high-vacuum mode scanning electron microscopies complement each other in comprehensive study of biogeochemical role of microscopic fungi in transformations of metals and minerals.