ΦCrAss001, a member of the most abundant bacteriophage family in the human gut, infects Bacteroides
{Phi}CrAss001, isolated from human faecal material, is the first member of the extensive crAssphage family to be grown in pure culture. The bacteriophage infects the human gut symbiont Bacteroides intestinalis, confirming in silico predictions of the likely host. Genome analysis demonstrated that the phage DNA is 102 kb in size, has an unusual genome organisation and does not possess any obvious genes for lysogeny. In addition, electron microscopy confirms that {varphi}crAss001 has a podovirus-like morphology. Despite the absence of lysogeny genes, {varphi}crAss001 replicates in a way that does not disrupt proliferation of the host bacterium and is able to maintain itself in continuous host culture.