Characterization of a new bacteriophage which infects bacteria of the genus Acidiphilium

1 Biotechnology, Idaho National Engineering Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415-2203 and 2 Department of Biological Sciences, Idaho State University, Pocatello, Idaho 83201, U.S.A. A novel bacteriophage, termed Ac1, that infects strains of the genus Acidiphilium (acidophilic, heterotrophic, aerobic, Gram-negative eubacteria) most commonly isolated from acidic mine drainage environments, has been discovered and several of its properties have been determined. This is the first report of a bacteriophage infecting such cells. The virion has a lambdoid morphology and is larger than , as shown by electron microscopy and sucrose gradient centrifugation. The sedimentation coefficient of the virion is approximately 615S. The nucleic acid of Ac1 is dsDNA, approximately 102 kb in length. Several experimental results show that Ac1 is a temperate phage. The plaques are turbid, and most cells isolated from plaques produced on sensitive cells by filter-sterilized phage preparations contain the phage and are resistant to further phage infection. Southern blot analysis shows that Ac1 prophage DNA is integrated into the bacterial genome during the temperate growth phase. Present address: Department of Biochemistry, Colorado State University, Fort Collins, Colorado 80523, U.S.A. Received 2 April 1993; accepted 9 July 1993.