[Studies on the isolation and biological characterization of actinophages infecting Micromonospora sp. 40027].

Three actinophages, phiHAU7, phiHAU9 and phiHAU11, were isolated from soil using Micromonospora sp. 40027 as a indicator strain. Three phages showed very narrow host-ranges. Three phages could infect both Micromonospora sp. 40027 and Micromonospora A-M-01, phiHAU9 and phiHAU11 could also form plaques on Micromonospora purprea. All of the three phage particles have the hexagonal heads and tails; the plaque formation of three phages on Micromonospora sp. 40027 were best on DNA medium with addition of 32 mM Ca2+ and 30 mM Mg2+; phiHAU7 was stable at pH 6-12, and other phages were stable at pH 6-10; the suitable incubation temperature for the propagation of three phages was between 28 degrees C - 37 degrees C; 53% of phiHAU7 remained viable and none of other phages was alive when they were incubated at 60 degrees C for 30 min. Restriction digestion analysis of genomes of three phages indicated that they were all double-stranded DNA with cohesive ends, their genome size are ca. 60 kb, 58 kb and 55 kb, respectively.