Identification and classification of virulent bacteriophages of streptococcus thermophilus and Lactobacillus bulgaricus based on their replication parameters, capsid protein profiles and restriction endonuclease analysis

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In this thesis, we have determined DNA restriction patterns, structural protein analysis and
replication parameters of 26 S. thermophilus (709, 231, B3) and 24 Lb. bulgaricus (Y4, V1, V2)
phages. Furthermore, sensitivities of natural and commercial S. thermophilus and Lb. bulgaricus
strains to both of B3 S. thermophilus and 231 V1, V2 Lb. bulgaricus phages have been
investigated. It has been observed that none of the phages lyse natural S. thermophilus strain while
natural Lb. bulgaricus strains have shown to be sensitive to Lb. bulgaricus phages. Besides, some
of natural Lb. bulgaricus strains show sensitivity to some S. thermophilus phages as a heterolog
hosts. We have also identified that the electrophoretic profiles of the structural proteins of S.
thermophilus phages are related, with two major bands of 30.6 and 27.3 kDa in common for all
phages. Lb. bulgaricus phages, on the other hand, possess two and/or three major (29.6, 29.2, 26.2
kDa) and minor (100.8, 65, 50 kDa) structural proteins. We have classified these phages into five
groups based on major and minor proteins. EcoRI, EcoRV, PvuII, HindIII, ClaI, HaeII, HhaI,
PstI,and BamHI resriction endonücleases have been used to digest of S. thermophilus phages.
According to the EcoRV digestion, S. thermophilus phages are differentiated into nine subgroups.
The genom size (41-45 kb) of S. thermophilus phage is determined by summing the molecular size
of restriction fragments generated by digestion. Lb. bulgaricus phages are also treated with
restriction endonücleases (EcoRI, EcoRV, PvuII, HindIII, HhaI, and BamHI). The genom size
ranges from 29-32 kb. One-step growth studies show that latent periods of S. thermophilus phages
vary from 15 to 35 minutes and latent period of ΦY4-X12 is 85 minutes. Finally, it has been
observed that all phages have similar rising time whereas they considerably differ in the size of
burst.

Esra Acar Soykut
Streptococcus thermophilus ve Lactobacillus bulgaricus virülent fajlarının replikasyon parametreleri, kapsid protein profilleri ve restriksiyon endonükleaz analizleri esas alınarak tanımlanmaları ve sınıflandırılmaları · 2007 · 186 sayfa.
Danışman: Prof.Dr. Nezihe Tunail
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