الفهرس | Only 14 pages are availabe for public view |
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. |