Pattern of cell division in ∼3.4 Ga-old microbes from South Africa

Abstract

In cell division, most microbes rely on binary fission. Some, however, show less common division patterns, such as multiple fission or budding. Little is known about the nature of cell division in the Earth’s earliest fossil microbes, largely because of their poor preservation, but such details could be key in establishing the biogenicity of putative Archean fossils and their relationships to modern microbes. In this report we describe cellularly preserved microfossils from Paleoarchean (∼3.4-Ga-old) deposits of South Africa (Kromberg Formation). Their cellularity is revealed by well-preserved reproduction patterns exemplified by binary (symmetrical and asymmetrical) and multiple (coupled and/or sequential) cell fission. Although no clues concerning physiology or affinity of the studied cells can be drawn basing on their division mode, the identified reproductive patterns link them particularly closely with coccoidal microbes classified within the cyanobacterial group Pleurocapsales.