الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
, A bacteriocin is a protein produced by microorganisms which have , the capacity to inhibit the growth of other related strains. The formation of a given bacteriocin is mostly dependent on the presence of a corresponding plasmid. Bacteriocins are much more potent than antibiotics and have a more narrow antimicrobial spectrum. Some bacteriocins are nucleases and attack DNA, others act on the cytoplasmic membrane, increasing its permeability to ions or inhibiting active transport. It is possible that bacteriocins may influence the microbial ecology of the oral cavity, however, bacteriocins produced by oral bacteria have not yet been fully characterized.
A total of 78 bacterial strains isolated from the dental plaque of different individual volonteers were tested for their ability to produce antibacterial agent against the indicator strain Streptococcus miitans (KPSK2). The indicator strain a human pathogenic bacteria forming dental plaque and causing dental caries. Six of the tested strains showed positive inhibitory effect against S. nnitans. The strain showed the highest ability to produce the antibacterial agent in liquid culture, was selected for further characterization.