Bdellovibrio bacteriovorusare smallDeltaproteobacteriathat invade, kill and assimilate their prey. Metagenomic assembly analysis of the microbial mats of an arsenic rich, hot spring was performed to describe the genotypes of the predatorBdellovibrioand the ecogenetically adapted taxaEnterobacter. The microbial mats were enriched withBdellovibrio(1.3%) and several Gram-negative bacteria includingBordetella(16%),Enterobacter(6.8%),Burkholderia(4.8%),Acinetobacter(2.3%) andYersinia(1%). A high-quality (47 contigs, 25X coverage; 3.5 Mbp) draft genome ofBdellovibrio(strain ArHS; Arsenic Hot Spring) was reassembled, which lacked the marker geneBd0108associated with the usual method of prey interaction and invasion for this genus, while maintaining genes coding for the hydrolytic enzymes necessary for prey assimilation. By filtering microbial mat samples (< 0.45 μm) to enrich for small predatory cell sizes, we observedBdellovibrio-like cells attached side-on toE. colithrough electron microscopy. Furthermore, a draft pan-genome of the dominant potential host taxon,Enterobacter cloacaeArHS (4.8 Mb), along with three of its viral genotypes (n= 3; 42 kb, 49 kb and 50 kb), was assembled. These data were further used to analyse the population level evolutionary dynamics (taxonomical and functional) of reconstructed genotypes.