Bdellovibrio host dependence: the search for signal molecules and genes that regulate the intraperiplasmic growth cycle

In 1962, while attempting to isolate bacteriophage from soil samples, Stolp and Petzhold (29) noted a number of odd plaques. Instead of taking hours to appear, these plaques took days to develop and continued to grow in size for more than a week. Intrigued, the investigators examined some of the plaque material under the light microscope