Discovery of a Conjugative Megaplasmid in Bifidobacterium breve

Abstract

ABSTRACTBifidobacterium breveis a common and sometimes very abundant inhabitant of the human gut. Genome sequencing ofB. breveJCM 7017 revealed the presence of an extrachromosomal element, designated pMP7017 consisting of >190 kb, thus representing the first reported bifidobacterial megaplasmid.In silicocharacterization of this element revealed several genomic features supporting a stable establishment of the megaplasmid in its host, illustrated by predicted CRISPR-Cas functions that are known to protect the host against intrusion of foreign DNA. Interestingly, pMP7017 is also predicted to encode a conjugative DNA transfer apparatus and, consistent with this notion, we demonstrate here the conjugal transfer of pMP7017 to representative strains ofB. breveandB. longumsubsp.longum. We also demonstrate the presence of a megaplasmid with homology to pMP7017 in threeB. longumsubsp.longumstrains.