Mycoplasma Phages

Abstract Mycoplasma (with no italics) is the generic name for the small, wall-less bacteria that arose by degen- erate evolution from the Streptococcus branch of the Grampositive bacteria phylogenetic tree (25). At present these microorganisms are grouped into one putative genus plus eight well-accepted genera including the Acholeplasma, Spiroplasma, and Mycoplasma together forming the order Mollicutes (table 40-1). Mycoplasma genera have diverse habitats and biochemical and physiological properties. The genomes of some species are only 600^800 kbp. The first mycoplasma phage was isolated in 1970 by R. N. Gourlay in England, using a bovine mycoplasma isolate as host cells and filtrates of bovine mycoplasma isolates as the phage source (16). Subsequently the host strain was identified as Acholeplasma laidlawii and the phage was identified as a filamentous phage containing single-stranded DNA. Over the next few years Gourlay isolated enveloped quasi-spherical phages as well as short-tailed phages infecting A. laidlawii. Since then, other workers have isolated more Acholeplasma phages as well as phages infecting Spiroplasma and Mycoplasma strains (23, 24). Phages active against other Mollicutes genera have not been isolated.