Morphology and General Characteristics of Lytic Phages Infective on Strains of Bradyrhizobium japonicum

Abstract

Biological characteristics of three isolated phages (SR1, SR2, and SR3) lytic against three Bradyrhizobium japonicum strains were studied. These phages had no cross-infectivity among the host strains. Phage morphology indicates that they belonged to Siphoviridae (long noncontractile tail; SR1 and SR2) and Podoviridae (short tail; SR3) classes of bacteriophages. Lytic cycle of phages studied under identical conditions showed a distinct adsorption rate (67.3-99.1%), latent period (150-300 min), rise period (60-150 min), and burst size (110-200 pfu/cell). Stability in liquids and inactivation by osmotic shock, thermal, and ultraviolet irradiation were also distinct in this heterogeneous phage group. Influence of soil factors such as temperature, soil moisture, soil pH, and degree of phage adsorption to the soil on phage survival was determined. Major percent of free infective phages were obtained after desorption of phages from soil. Overall, temperature appeared to be the most important parameter affecting rhizobiophage survival in the soil.

Complete Genome of the Xanthomonas euvesicatoria Specific Bacteriophage KΦ1, Its Survival and Potential in Control of Pepper Bacterial Spot

“…On the contrary, phage concentration in sterile distilled water significantly decreased during 3 weeks. Similar results were reported by Appunu and Dhar (2008), who studied the stability of phage in distilled water, saline solution and YM broth. After 30 days at 4°C in distilled water, there were no viable phage particles, whereas in other media titer declined much more slowly.…”

“…After 30 days at 4°C in distilled water, there were no viable phage particles, whereas in other media titer declined much more slowly. The differences in phage stability in media may be due to the interaction of phage coat proteins with cations, anions and organic molecules present in the medium (Appunu and Dhar, 2008). Temperature is an important factor affecting phage stability.…”

Identification and characterization of phages parasitic on bradyrhizobia nodulating groundnut ( Arachis hypogaea L.) in South Africa

“…Phages PRSA-1 and PRSA-2 characteristically had tailfins, while PRSA-26 had none (Table 2). Notwithstanding the slight differences in head and tail dimensions, the TEM data revealed close similarity of these phage isolates to phage SR-2, which was reported to parasitize on Bradyrhizobium, and phage 2011 which parasitized on Rhizobium melilotii (Werquin et al, 1988, Appunu and Dhar, 2008). …”