Characterization of a new virulent phage theta MC1 specific to Microbulbifer strain CMC-5

Abstract

Microbulbifer strain CMC-5, isolated from decomposing seaweeds degrades agar, alginate, carrageenan, chitin, carboxymethyl cellulose and xylan. Using bacterial strain CMC-5 as host, a novel virulent phage, designated theta MC1 was isolated from the coast of Goa, India. Although theta MC1 demonstrated cross infectivity with type species of Microbulbifer such as M. agarolyticus JAMBA3 sup(T) and M. celer KCTC 12973 sup(T), it did not infect M. mangrovi KCTC 23483 sup(T), M. salipalidus JCM 11542 sup(T), M. elongatus DSM 6810 sup(T) and M. hydrolyticus IRE-31 sup(T). The one step growth experiment of theta MC1 infecting bacterial strain CMC-5 at a multiplicity of infection of 0.1, revealed a latent period of 60 min and a burst size of 180. TEM analysis of theta MC1 indicated it to be a tailless phage with an icosahedral head having a diameter of 60 plus or minus 1.42 nm. The ds DNA of theta MC1 was restricted by EcoRI, HindIII and SmaI whereas HaeIII, BamHI, PstI, NotI did not cleave the DNA. The molecular size of theta MC1 DNA was analyzed by restriction digestion as well as pulsed field gel electrophoresis and was estimated at 48.5 kb. The phage infectivity was adversely affected by organic solvents demonstrating the presence of a lipid membrane. The inhibition of theta MC1 infectivity by EDTA was abolished by addition of Ca and Mg salts.