Effect of Exogenous Spermine on Biofilm Formation in Mycobacteria by Stimulating the Synthesis of Glycopeptidolipids

Biofilm formation is of great interest by its ability to increase bacterial tolerance to antibiotics that represent a serious problem for modern medicine. Among mycobacteria, which are also capable of forming biofilms, there are pathogens of socially dangerous infections, including tuberculosis. Basing on these data, the strains of Mycolicibacterium smegmatis mc2 155 were chosen as the objects of this study, including the parent strain without deletions and its mutants with one (ΔrelMsm) and double (ΔrelMsmΔrelZ) chromosomal deletions of the genes responsible for the synthesis of alarmone synthetase enzymes. Biofilms of mutant strains exhibited defects in biofilm formation. We have shown that the integrity, hydrophobicity, and the level of biomass of surface mycobacterial biofilms are dependent on the amount of glycopeptidolipids (GPL) in cells. The level of GPL depends on the activity of alarmone synthetases. The biogenic polyamine spermine is able to enhance the production of GPLs, restoring the integrity of biofilms of mutant strains. It is possible that this effect of spermine is caused by the influence on the activity of mycobacterial alarmone synthetases, which makes promising the further studying the molecular mechanisms of its action.