CHARACTERIZATION OF VIRULENT BACTERIOPHAGES FOR STREPTOMYCES GRISEOFLAVUS ISOLATED FROM SOI

Abstract

Streptomyces griseoflavus and two of its specific phages were isolated from free
clay soil samples obtained from Al-Sharkia Governorate, Egypt. Streptomyces
phages were detected after their enrichment by the spot test. The specific phages
were isolated by the single plaque isolation technique; propagated by the liquid
enrichment method and purified by the polyethylene glycol, dextran sulfate two
phases system. The phages were signed as S1 and S2, referring to the genus
Streptomyces. S1 phage appeared with head (91 x 66 nm) and long contractile tail
(158 x 66 nm) and S2 phage had isometric head (112 nm) and a long non-contractile
tail with length of about 200 nm. The phages formed plaques differing in their sizes
3.0 and 7.0 mm for S1 and S2 phages, respectively. UV-absorption properties of the
phages were determined. Maximum absorption (Amax) of S1 and S2 phages was at
275 nm while their minimum absorption (Amin) was at 245 nm for S1 phage and 250
nm for S2 phage. The ratio between Amax/min was 1.407 for S1 phage and 1.553 for S2
phage and the ratio between A280/260 was 1.186 and 1.371 for S1 and S2 phages,
respectively. The host ranges were investigated with 5 species of Streptomyces.
Results showed that S1 phage, differ from S2 phage as it did not infect S.
noboritonesis and S. lincolnesis in contrast with S1 phage, which infect all the tested
Streptomyces species. The antisera specific for S1 and S2 phages were prepared and
serological relations were studied. Serological data revealed that, the two phages
were serologically related to each other