Initiation of intracellular offspring in <i>Epulopiscium</i>

Summary Epulopiscium spp. are the largest heterotrophic bacteria yet described. A distinguishing feature of the Epulopiscium group is their viviparous production of multiple, internal offspring as a means of cellular reproduction. Based on their phylogenetic position, among low G + C Gram‐positive endospore‐forming bacteria, and the remarkable morphological similarity between developing endospores and Epulopiscium offspring, we hypothesized that intracellular offspring production in Epulopiscium evolved from endospore formation. These observations also raise the possibility that a cell with the capacity to form multiple intracellular offspring was the ancestor of all contemporary endospore‐forming bacteria. In an effort to characterize mechanisms common to both processes, we describe the earliest stages of offspring formation in Epulopiscium . First, in anticipation of polar division, some of the mother cell DNA coalesces at the cell poles. FtsZ then localizes in a b