Sinorhizobium meliloti strains, inoculated with some lytic bacteriophage isolates

Abstract

Lysis by bacteriophages is one of the factors influencing growth and survival of rhizobia in soil. As specific bacteriophages, infective for the root-nodule bacterium Sinorhizobium meliloti, are wide spread and may be found in almost all alfalfa fields, it was of theortical and practical importance to examine phage-host interaction. In these investigations 64 strains of S. meliloti, with diverse origin and characteristics, were included. Ten specific bacteriophages, have been selected from those isolated by enrichment of soils. The infective ability of the bacteriophages was assessed accoding to the occurrence of plaques on inoculated double-layer agar plates. According to the differential susceptibility of individual S. meliloti strains to each phage, strains were divided into three different groups: 1. Bacterial strains (6) resistant to all tested bacteriophages; 2. Bacterial strains (12) susceptible to all tested bacteriophages; and 3. Bacterial strains (46) susceptible to some of the tested bacteriophages. Some of active nitrogen fixers from the first group could be useful in the nodulation of alfalfa plants.

Lizis prouzrokovan bakteriofagima je jedan od faktora koji utiče na porast i preživljavanje bakterija, simbioznih azotofiksatora u zemljištu. Kako su bakteriofagi specifični za kvržičnu bakteriju Sinorhizobium meliloti široko rasprostranjeni i mogu se naći u skoro svim lucerištima, bilo je od teorijskog i praktičnog značaja ispitati interakciju između faga i bakterija, njihovih domaćina. U ova istraživanja uključeno je 64 sojeva S. meliloti, različitog porekla i karakteristika. Izabrano je deset specifičnih bakteriofaga, izolovanih metodom obogaćivanja zemljišta. Infektivnost bakteriofaga za bakterijske sojeve određivana je na osnovu pojave plakova u inokulisanom dvostrukom agaru. Na osnovu različite osetljivosti svakog pojedinačnog soja S. meliloti prema testiranim izolatima bakteriofaga, bakterijski sojevi su podčijeni u tri grupe: 1. Bakterijski sojevi (6) rezistentni prema svim testiranim bakteriofagima; 2. Bakterijski sojevi (12) osetljivi prema svim testiranim bakteriofagima; i 3. Bakterijski sojevi (46) osetljivi prema nekim od testiranih bakteriofaga. Neki sojevi koji pripadaju prvoj grupi, a pokazuju visoku aktivnost u azotofiksaciji mogu biti korisni u nodulaciji licerke.