Acidiphilium multivorum AIU301^T was isolated as an acidophilic, aerobic, anoxygenic and phototrophic bacterium from pyritic acid mine drainage. Members of the genus Acidiphlium belonging to alpha-proteobacteria are well known to have high ability of resistance to various metals under acidic condition, and require high acidity for growth. A. multivorum AIU301^T is also characterized as a strain exhibiting tolerance to nickel, zinc, cadmium and copper ion. Furthermore, A. multivorum AIU301^T exhibits resistance to arsenate and arsenite. Also interesting is that A. multivorum AIU301^T has zinc-chelated-bacteriochlorophylls (Zn-Bchl) a rather than Mg-Bchl a as the major photopigment. This unique character is limited in a group of aerobic acidophilic proteobacteria including species of the genus Acidiphlium.

Genome analysis of A. multivorum AIU301^T revealed nine replicons composed of one circular chromosome (3,749,411 bp, 67.6% G+C, 3,449 ORF) and eight circular plasmids pACMV1 (271,573 bp, 62.9% G+C, 284 ORF), pACMV2 (65,564 bp, 61.9% G+C, 69 ORF), pACMV3 (54,248 bp, 61.2% G+C, 61 ORF), pACMV4 (40,588 bp, 60.1% G+C, 44 ORF), pACMV5 (14,328 bp, 59.0% G+C, 19 ORF), pACMV6 (12,125 bp, 59.6% G+C, 14 ORF), pACMV7 (5,178 bp, 57.6% G+C, 8 ORF) and pACMV8 (1,728 bp, 60.9% G+C, 1 ORF). The chromosome and circular plasmids encode many genes which seem to be involved in heavy metal-transport, and three operons which seem to contribute to arsenic resistance. A. multivorum AIU301^T chromosome showed overall high conservation of synteny with Acidipphilium cryptum JF-5 chromosome which has been sequenced, excluding a few regions. One of the unique regions that exist only in A. multivorum AIU301^T is a 225-kb region which contains the photosynthesis gene cluster and many insertion sequences.

The genome sequence of A. multivorum AIU301^T would provide insights into the understanding of acidophilic bacteria, and may also facilitate the development of technologies utilizing this bacterium such as bioremediation in acidic and metal-rich environment.