[Lysogeny of Rhizobium japonicum and the sensitivity of these cultures to phages isolated from soil].

Twenty cultures of Rhizobium japonicum of various origin were tested for lysogeny using a cross technique with a preliminary UV induction and without it as well as by electron microscopy. None of the cultures was found in the lysogenic state. Phages active against Rh. japonicum were detected in four soil samples on which soybean plants were grown; 27 phages were isolated by the enrichment method and 3 phages without enrichment. The phages were capable of lysis of only Rh. japonicum cultures and differed in the spectrum of lytic action. Some of them were very specific: 9 phages caused lysis of only one among the 28 tested cultures, and 10 phages lysed 2 cultures. Phages with a broad spectrum of lytic action induced lysis of 7-9 cultures. Some of the phages isolated from soils of different type were identical and some were similar in the spectrum of lytic action. Among 28 cultures of Rh. japonicum, 8 cultures were sensitive to all of the 30 phages isolated from soil and 2 cultures were sensitive to most of the phages; the remaining cultures were sensitive to 1-8 phages. Phages and cultures have been selected which can be used for experimental preparation of lysogenic systems and further studies of lysogeny in Rh. japonicum.