Abstract

Some genera of micro-organisms produce bacterial metabolites that have antibiotic effect against same species and to other genera of bacteria as well. The known bacteria which can affect the intact cells of other bacteria are mostly gram negative bacilli such as E. coli, Ps. aeruginosa, V. cholerae and Y. pestis. The most responsible substances inhibiting the bacterial growth are known grossly as bacteriocin, and subsequently named as colicin, pyocin, vibriocin and pesticin according to the bacteria from which these metabolites are derived. The study had been conducted to see the antagonistic effect of Ps. aeruginosa against some enteric bacteria, both pathogenes and normal flora, and gram positive cocci. The experiment yielded the following results: 1. The antagonistic effect of Ps. aeruginosa against the testing strains was confirmed, but the degree of the effect varied not only depending upon the age of the strains, but also to the organisms. 2. Dilution of the Ps. aerugionsa bacterial suspension decreased the potency of the effect, however, rendered the quantitative estimation of the inhibitory effect. 3. The quantitative analysis showed that the antagonistic effect of Ps. aeruginosa proved weaker against the other genera of bacteria than against the same species. This definite difference in degree of inhibitory action indicated the possibility of its application in the identification of the clinical bacteriology employing the principle of the type specificity. 4. It was also interesting that the antagonistic effect of Ps. aeruginosa was not only inhibitory against gram negative bacilli, but also against the highly resistant gram-positive cocci, Staphylococcus aureus.