Document Type : Research Paper
Department of Microbiology, Faculty of Biological Sciences, Falavarjan Branch, Islamic Azad University
The aggregation of oral Streptococci is resulted in the commence of enamel calcium degradation of the teeth and subsequently emergence of dental caries. The bacteriophages have considerable effects in controlling the populations of various bacteria. The isolation and characterization of specific lytic bacteriophages against oral streptococci were the main goals of this study. The BHI culture medium was used for oral streptococci enrichment from dental plaque. The MSA culture medium was applied to isolate oral streptococci from dental plaque samples. The membrane filtrate of Caspian Sea water was added to streptococcal isolate suspension and cultured using overlay method. The isolated bacterium on MSA according to macroscopic, microscopic and biochemical examinations identified as Streptococcus salivarius. The BLASTN of gtfK gene after DNA sequencing reconfirmed that our isolate was S. salivarius. The strain was named S. salivarius KBM-ISF-2 and its gtfK gene was deposited at GenBank, NCBI under accession number of KJ634208.1 Transmission electron microscopy revealed two specific lytic bacteriophages that attacked S. salivarius we isolated from dental plaques. The first lytic phage was a Tectivirus with icosahedral symmetry measuring 46.67 nm as thickness. The second phage was a Cystovirus with icosahedral symmetry and diameter of 85.56 nm. This is the first report of isolation and characterization of Tectiviruses and Cystoviruses from Caspian Sea and their specific preventing effects on oral streptococci. The lytic specific bacteriophages could be applied as a therapeutic measure for preventing the infectious diseases in human oral cavity.