TITLE:
Isolation and Characterization of Bacteriophages from Laban Jameed
AUTHORS:
Murad Mohammad Ishnaiwer, Fawzi Al-Razem
KEYWORDS:
Lactic Acid Bacteria; Bacteriophages; Laban Jameed; DNA Viruses; RNA Viruses
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.4 No.11A,
November
6,
2013
ABSTRACT: Laban jameed is a dried salty dairy
product obtained by fermentation of milk using a complex population of lactic
acid bacteria. Jameed is considered a traditional food product in most eastern
Mediterranean countries and is usually made from sheep or cow milk. The aim of
this study was to assess phage contamination of jameed dairy product. Two
phages were isolated: one from sheep milk jameed (PPUDV) and the other from cow
milk jameed (PPURV). Each of the two bacteriophages was partially
characterized. The PPUDV phage was identified as a single stranded DNA virus
with an approximately 20 kb genome that was resistant to RNase, whereas PPURV
phage possessed a double stranded RNA genome of approximately 20 kb and was
resistant to DNase. The phage bacterial strain hosts were identified as Lactobacillus
helveticus and Bacillus amyloliquefaciens for PPUDV and PPURV,
respectively. One step growth curve using a double layer plaque assay test was
carried out to monitor the phage life cycle after host infection. PPUDV showed
a latent period of about 36 h, burst period of 70 h and a burst size of about
600 Plaque Forming Units (PFU) per infected cell. PPURV phage showed a latent
period of about 24 h, burst period of 47 h and a burst size of about 700 PFU
per infected cell. SDS-PAGE analysis of total viral proteins showed at least
three major bands (27, 40, and 45 kDa) for PPUDV. This is the first study to
report the isolation of both DNA and RNA bacteriophages from laban jameed. This
study adds new insights into the complexity of dairy contamination and
fermentation microbiology of the jameed revealing the existence of two viral
genomes in this highly dried and salty dairy product.