Abstract
The transition of active Mycolicibacterium smegmatis cells to a dormant state under acidi cation conditions is associated with intracellular accumulation of coproporphyrin tetramethyl ether (TMC). At the same time, dormant forms of mycobacteria develop resistance to a number of damaging factors. The addition of 5-aminolevulinic acid (ALA), a precursor of porphyrin synthesis, into the bacterial culture medium leads to the accumulation of TMC in actively growing cells, that simulates the situation with dormant mycobacteria. With an increase in the concentration of TMC by 3 times, the bacteria become 7 times more resistant to the action of 40 mM hydrogen peroxide and 90 times more resistant to heating up to 80 °C. At the same time, in M. smegmatis cells with an increased content of TMC, the activity of dichlorophenolindophenol reductase, which is a marker of respiratory chain activity, decreases by 18%. The detected inhibition of activity can lead to a decrease in side oxidative reactions in the cell. Thus, the accumulation of methylated coproporphyrin is possible to be one of the mechanisms for the development of mycobacterium resistance at dormancy.
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