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The quality of bacteriophage electron microscopy appears to be on a downward course since the 1980s. This coincides with the introduction of digital electron microscopes and a general lowering of standards, possibly due to the disappearance of several world-class electron microscopists The most important problem seems to be poor contrast. Positive staining is frequently not recognized as an undesirable artifact. Phage parts, bacterial debris, and aberrant or damaged phage particles may be misdiagnosed as bacterial viruses. Digital electron microscopes often seem to be operated without magnification control because this is difficult and inconvenient. In summary, most phage electron microscopy problems may be attributed to human failure. Journals are a last-ditch defense and have a heavy responsibility in selecting competent reviewers and rejecting, or not, unsatisfactory articles.

A total of 30,000 phage papers, books, or book chapters, published between 1965 and 2010, were analyzed for the ethnic origins of 14,429 first authors. Their names represent 40 linguistic domains or geographic areas and at least 70 languages. British and German names predominate. Results broadly concur with statistics on the frequency of publications by country and show the growing role of Third-World countries in phage research. Irish and Jewish scientists are prominent. Historical and societal factors appear to be very important elements in the advancement of science.

Phages are among the simplest biological entities known and simultaneously the most numerous and ubiquitous members of the biosphere. Among the three families of tailed dsDNA phages, the Myoviridae have the most structurally sophisticated tails which are capable of contraction, unlike the simpler tails of the Podoviridae and Siphoviridae. Such “nanomachines” tails are involved in both efficient phage adsorption and genome injection. Their structural complexity probably necessitates multistep morphogenetic pathways, involving non-structural components, to correctly assemble the structural constituents. For reasons probably related, at least in part, to such morphological intricacy, myoviruses tend to have larger genomes than simpler phages. As a consequence, there are no well-characterized myoviruses with a size of less than 40 kb. Here we report on the characterization and sequencing of the 23,931 bp genome of the dwarf myovirus ϕ1402 of Bdellovibrio bacteriovorus. Our genomic analysis shows that ϕ1402 differs substantially from all other known phages and appears to be the smallest known autonomous myovirus.

After attempts to obtain high-magnification pictures of bacteria in the hypermicroscope had shown that bacterial structures of sub-light-microscopical magnification could be visualized, a precondit...

The first phage electron micrographs were published in 1940 in Germany and proved the particulate nature of bacteriophages. Phages and infected bacteria were first examined raw and unstained. US American scientists introduced shadowing and freeze-drying. Phages appeared to be tailed and morphologically heterogeneous. Phage types identified by early electron microscopy include enterobacteriophages T4, T1, T7, T5, 7–11, ViI and Pseudomonas phage PB1. This paper retraces the development of early virus electron microscopy till the introduction of negative staining.

If a filtered bacteria-free phage lysate of a broth culture of coli bacteria is shaken with aluminum oxide C g, the phosphate-containing high-molecular phage protein is adsorbed preferentially. It can be eluted again from the centrifuged and washed adsorbant by means of a phosphate buffer (m/10 to m/30, pH 7). This adsorption procedure is repeated several consecutive times on the lysate [and] the eluates are pooled and dialyzed until the removal of phosphate ions. The adsorption procedure can be repeated on the purified phage solution. Freshly precipitated aluminum oxide is also suitable for adsorption; it adsorbs better, but is apparently less selective. More details on the technique will be communicated soon. The success of the adsorption technique is illustrated by the following example. In a phage assay (0.5 ml phage solution + 5.0 ml coli broth), a lysate pre-purified by aluminum oxide C g was still lytic after dilution to a protein content of 2 × 10−12 g/ml (visibly positive = +). The pure phage solution prepared from this lysate, with a protein content of 3 × 10−15 g/ml, was strongly lytic (+++) in the phage assay. The smallest lytic protein quantity is probably 1–3 × 10−16 g. Starting from the assumption that bacteriophages, like phytopathogenic viruses, are high-molecular protein bodies, the maximal molecular weight of a phage may be calculated as about 100 millions. The diameter of the[se] supposedly spherical molecules is thus approximately 60 mm. The specific clouding of the protein increases with growing purity. The above-mentioned lysate had a specific opacity of 0.8 and the phage solution here had an opacity of 22 (values in other cases were 10–22). If such phage solutions are examined in the Siemens-hypermicroscope of E. Ruska and B. v. Borries according to the technique developed for other viruses, one obtains images as shown in Fig. 1 and ​and2.2. Phages appear in pure preparations as very small rounded corpuscles (Fig. 1), whose dimensions seem to depend on the phage protein concentration in the solution, so that higher concentrations lead to larger aggregates. The phage solution seems to become more homodisperse in higher dilutions. Isolated corpuscles show then diameters of 40–80 mm. These values are of the same order of magnitude as the particle diameter calculated above from (biological) activity. Presently, it cannot be decided whether we are in presence of phage protein molecules or still aggregates. It was observed with certainty that phages can be destroyed by long and intensive electron irradiation, leaving round, hollow structures behind. In addition, we refer to the article of H. Ruska, in this issue, on the visualization of bacteriophage lysis. Fig. 1. III 73/39. Highly purified suspension of coliphages, strongly lytic till 10 g/ml. El. opt. : 25 000:1. Fig. 2. III 71/39. As Fig. 1 after intensive and prolonged electron irradiation. El. opt. : 22 000:1. Berlin-Dahlem, Biologische Reichsanstalt fur Land- und Forstwirtschaft, and Berlin-Siemensstadt, Electron Optics Laboratory of Siemens & Halske A.G.

Anna Sergeyevna Tikhonenko (1925–2010) is to be remembered for the excellency of her electron microscopical work, particularly with bacteriophages. She published 113 articles and one book, Ultrastructure of Bacterial Viruses (Izdadelstvo Nauka, Moscow 1968; Plenum Press, New York, 1972). It included 134 micrographs and a complete overview of the 316 phages then examined by electron microscopy. Most micrographs were of exceptional quality. This book, a rarity in those days of strict separation of Soviet and Western research, was the first bacteriophage atlas in the literature and presented a morphological classification of phages into five categories of family level, similar to a scheme presented in 1965 by D.E. Bradley (J Royal Microsc Soc 84:257–316). Her book remains one of the fundamentals of phage research.

Hans-W. AckermannI was born in 1936 in Berlin, Germany. I attended the College Francais Berlin, a historical school where all the classes are taught in French. Although living in East Berlin, I stu...