Challenges Confronted by Electron Microscopy in Microbe Detection

Electron microscopy has been contributing significantly to the study of microbes for biomedical, biological, and material science purposes in the world. Besides providing structural information, precise chemical analysis can be carried out by determining sample composition in thin films by Energy- Dispersive X-ray Spectroscopy (EDS) or Electron Energy Loss Spectroscopy (EELS), along with observing materials and specimens in the nano-level. It can also help in formulating new technologies to aid humans in countless applications. At times, when focusing an electron beam on any surface, various elastic and inelastic interactions occur within the material. A couple of essential issues that occur with obtaining high-resolution Scanning Electron Microscope images of microbes are - a) to get adequate contrast, one need to condense the charging time for small organic particles such as bacteria and viruses that require magnifications greater than 1000x, thus, an appropriate conducting surface is essential; & b) biological specimens need to be first dehydrated from original condition, for the appropriate imaging performance for the Scanning electron Microscope. The prominent limitation to date yet to be unraveled in electron microscopy is that none of them reveal the phylogenetic diversity of the microorganisms present in the study habitat. Unless detection schemes are developed allowing at least 3 orders of magnitude lower electron doses, the ability of electron microscopy to study life cell processes at the nanoscale, although very attractive, probably remains an idea concept. This review summarizes the difficulty in microbe detection and numerous encounters faced by Electron Microscopy in doing so.