Visualising microorganisms from molecules to cells

Visual methods have been a central part of the study of microbial life since its beginnings. Microbiologists have used increasingly sophisticated microscopes to examine living cells, and fixed, stained and labelled cells, in clever ways to reveal their inner secrets. As part of their work, scientists have documented their findings with photographs, illustrations and models of the cells and their properties. These visual methods have played an important role in presenting microbial research in the FEMS journals. In this second of the four 40th anniversary Commentaries, images from 10 FEMS articles have been chosen to exemplify the diversity of visualisation used in microbiology. Read on to find out how far microbial imaging has come in the last 40 years. Microscopy led to the initial discovery and classification of bacteria and, today, advanced methods are revealing the inner molecular structure. The pages of FEMS journals are filled with micrographs from light microscopy and electron microscopy. In some cases, these micrographs stand alone. The freeze-etched SEM image of the surface of a Pyrodictium cell (Fig. 1; Rachel et al. , 1997) reveals a surface studded with the hexagonal proteins of an S-layer, as well as a bundle of tubules extending from the upper right region, providing interconnections to neighbouring cells. S-layer proteins are found on the surface of some bacteria, archaea and algae. The archaeon Pyrodictium was isolated from a deep-sea hydrothermal vent and was the first organism found to grow at temperatures above 100 °C. Its S-layer is assumed to provide mechanical, osmotic and possibly thermal stability. Freeze-etched scanning electron microscopy image of the surface of a Pyrodictium cell (from Rachel et al ., 1997). In the past two decades, fluorescence …