Assessment of the applicability of primarily identified natural luminescent bacteria, isolated from the azov and the black seas, to determine the antimicrobial activity of antibiotics

Abstract

Five isolates of luminous bacteria from aquatic organisms of the Azov and the Black Seas were isolated. The study of morphological, cultural, physiological and biochemical properties showed that isolates M1 and M4 were the representatives of the species harveyi, and isolates Fb, Sh1, and B were the representatives of the species P. leiognathi. It was found that the strain P. leiognathi Sh1 was the most sensitive to zinc sulfate when studying its effect on allocated luminescent bacteria. The effective concentration that reduced the bioluminescent index (BLI) by 50% (EC50) for zinc sulfate, when exposed to the test strain, was 4,0 0,1 g/ml. Experimental data allowed to consider the strain P. leiognathi Sh1 to be the test-object for determining the antimicrobial activity of benzylpenicillin, gentamicin, streptomycin, tetracycline and ceftriaxone. The results of evaluating the effect of antibiotics on the test object, revealed that after 15 minutes of incubation, the BLI values decreased by 50% only in samples containing benzylpenicillin, gentamicin, and tetracycline. Their EC50 were 500.0, 283.0 and 28.5 g/ml respectively. It was found that the exposure of test-strain to all antibacterial agents demonstrated resulted in decrease in BLI by 100% as compared to the control values. Strain P. leiognathi Sh1 can be used as a test-object for determining the antimicrobial activity of antibiotics.