Specialized Transduction of a Cysteine Marker by Rhizobium meliloti Phage 16-3

Specialized transduction by phage 16-3 of one of the cys markers of Rhizobium meliloti is described. The frequency of transduction was 10−6 to 10−7 per plaque-forming unit. About two-thirds of the transductants were heterogenotes, unstable for the cys+ marker, and yielded high frequency transducing lysates (10−2 per plaque-forming unit). In phage lysates, plaque-forming transducing particles were directly demonstrated while non-plaque-forming particles were only detected indirectly via complementation of defective lysogenic transductants. In the defective transductants, the two distal ends of the vegetative phage map were lacking. By plasmid transfer, the attachment site of phage 16-3 was located close to the cys-46 and met-5 markers. Transduction of the met-5 marker could not be demonstrated

Mann Zoltán Ádám CORBA alkalmazások nyomkövetése interceptor-ok segítségével

2. Elosztott objektum-orientált rendszerek.................................................................................................................

ISOLATION AND CHARACTERIZATION OF AN R-PRIME PLASMID FROM RHIZOBIUM-MELILOTI

Using a simple enrichment procedure, we isolated an R-prime derivative of plasmid R68.45 carrying a 17.8-megadalton segment of the Rhizobium meliloti 41 chromosome. The chromosomal segment carried on this plasmid (pGY1) includes the markers cys-24+, cys-46, and att,s6. Plasmid pGY1 mobilized the chromosome in a polarized way starting from the region of homology, but cannot promote chromosome transfer from other sites. The attlsC3 site on pGY1 allowed the integration of phage 16-3 into pGY1, and a composite plasmid of 91.8 megadaltons was formed. This vector (pGY2) is suitable for the introduction of Rhizobium bacteriophage 16-3 into other gram-negative bacteria