Morphological Investigations of the Fine Structure of Freshwater Diatom Frustules

Abstract

The diatom frustules are variously perforated and heavily ornamented due to regular deposition of siliceous material in different patterns. These species-specific patterning on the silica cell wall of diatoms forms a base for their identification as well as taxonomic classification. The cleaned frustules were observed under SEM to confirm the size of the porous silica. In the present investigation, Nitzschia, Cymbella, Encyonema, Pinnularia, Navicula, Planothidium, Frustulia, Eunotia, Surirella and Achnanthidium showed excellent porous silica in nanometer scale under SEM observation. SEM-EDS analysis showed two distinct peaks of silicon (Si) and oxygen (O) which confirmed that frustule is composed of amorphous silica in the form of SiO₂. Based on the present findings, it can be concluded that few freshwater diatoms obtained from these study areas possess excellent silica nanoporous structures which could be exploited in new emerging fields like nanoscience and technology.