Reply to “Concerns about Transmission Electron Micrographs in Recent Article by Chen and Williams”

Abstract

This is in response to the letter submitted by Dr. Susan Koval (1) regarding our recently published paper in mBio in April 2012 entitled “Sharing of prey: coinfection of a bacterium by a virus and a prokaryotic predator” (2). Dr. Koval cites her expertise in electron microscopy (EM) and on the prokaryotic predators Bdellovibrio and Bdellovibrio- like organisms (BALOs), which include the genus Bacteriovorax , a focus of our report. She suggests that our conclusions based on EM observations are erroneous. In attempts to support her argument, she cites several examples. First, she states that the legend to Fig. 1 is incorrect in that the electron micrographs do not show a predator residing inside the prey cell and that the cells we refer to as bdelloplasts appear to her to be plasmolyzed Vibrio vulnificus cells. She bases this on her opinion (as she states in her letter) that “two things” typically observed in a bdelloblast, “the prey cell protoplast” and the growing predator or BALO, are not seen in Fig. 1 micrographs and only one structure is present. I am surprised that Dr. Koval would not be better informed on this matter, as the evidence and facts have been documented widely in the literature. During the intraperiplasmic cell cycle, BALO consumes its prey’s protoplasm to obtain energy for its growth (elongation) (3). The volume of prey cell protoplasm remaining in the bdelloplast and observed by EM at any given point in time in the infection cycle depends …