الفهرس 
Classification of lactic acid bacteriaOnly 14 pages are availabe for public view
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Abstract
In this study Lactobacillus bacteria were isolated from it’s natural sources as (raw
milk, whey, different yogurts and cheeses) and identified by 16s rDNA in SIGMA
lab. It’s specific phages were isolated and designated as LPS1 and LPS2 phages,
physical and chemical characters were studied and the results showed that the LPS1
plaques’ were small in size, clear and it’s diameter approximately 2.7 nm, LPS2
plaques’ were large in size, clear and it’s diameter approximately 3.5 nm. Electron
microscopy of LPS1 phage showed that it belonged to Siphoviridae family with head
diameter of approximately 27 nm and tail length of approximately 80 nm, but LPS2
phage belonged to Podoviridae family with head diameter approximately 59.72 nm
and tailless. The physical properties of the isolated phages showed that these phages
were completely inactivated at temperature above 70°C. The highest activity of
LPS1 phage was at pH ranged between 4 and 9, but LPS2 phage was active at pH
ranged between 6.8 and 10. Laminar UV lamb showed no effect on the isolated
phages. SDS–PAGE of structural protein from bacteriophages/LPS1 and LPS2,
showed that the molecular weight of protein of LPS1 phage was approximately 28
kDa, but of LPS2 phage was approximately 31.5 kDa. Studying chemical properties
of the isolated phages showed that it’s DNA is dsDNA. The genome size roughly
estimated from restriction fragments, and was approximately 30:35 kbp. Results
showed that environmental stresses as high salt concentrations had anti phage
activities. The phages were also tested against vitamin C and plants extracts.
Key words: LAB, bacteriophage, antiphage, physical and chemical properties.