TOLERANCE TO ANTIMICROBIAL AGENTS AND PERSISTENCE OF <i>Escherichia coli </i>AND CYANOBACTERIA
Bacterial persistence is the tolerance of a small part of a cell population to bacterial agents that is attained by the suppression of important cell functions and subsequent deceleration or cessation of the cell division. The growth rate is the decisive factor in the transition of the cells to the persister state. A comparative study of quick-growing Escherichia coli K-12 strain MC 4100 and cyanobacteria Synechocystis sp. PCC 6803 and Anabaena variabilis ATCC 29413 that grow slowly was conducted. The cyanobacterial cells, much like E. coli, differed in the sensitivity to antimicrobial compounds depending on growth phase. Carbenicillin inhibiting the synthesis of peptidoglycan, a component of the bacterial cell wall, and lincomycin inhibiting protein synthesis gave rise to nucleoid decay in cells from exponential cultures of Synechocystis 6803 and did not influence the nucleoids in cells from stationary cultures. Carbenicillin suppressed the growth of exponential cultures and had no effect on stationary cyanobacterial cultures. The suppression of Synechocystis 6803 growth in the exponential phase by lincomycin was stronger than in the stationary phase. Similar data were obtained with cyanobacterial cells under the action of H2O2 or menadione, an inducer of generation of reactive oxygen species. Slow-growing cyanobacteria were similar to quick-growing E. coli in their characteristics. Persistence is characteristic of cyanobacteria.