Polyphosphate Affects the Biofilm Structure of Mycobacterium Smegmatis and its Survivability in Macrophage

The most unique characteristic of Mycobacterium tuberculosis is persistence in the human host and the biofilm formation is related to the persistance. Inorganic polyphosphate (polyP) is a chain molecule linked by high-energy phosphate bonds, which is considered to play a very important role in bacterial persistence. The relationship of polyP and mycobacterial biofilm formation is still adequately unclear. We constructed ppk mutant of M. smegmatis to observe the phenotype and microstructure of the biofilm and analyze the lipid levels and susceptibility to vancomycin antibiotic. And then wild, mutant and complemented strains were used to infect macrophages and analyze the expression levels of various inflammatory factor, respectively. polyP deficiency altered the phenotype and microstructure of the biofilm and reduced the cell lipid composition (except for C16.1 and C17.1, most of the fatty acid components from C8-C24). Moreover, the polyP-deficient mutant was also significantly more sensitive to vancomycin which targets the cell wall, and its ability to survive in macrophages decreased, which was related to the change of the expression level of inflammatory factors in macrophage. This study demonstrates that the polyP levels can affect the biofilm structure through affecting the content of short chain fatty acid and promote intracellular survival of M. smegmatis by altering the expression of inflammatory factors. These findings establish that polyP may be a potential target for the treatment of persistent infection of M. tuberculosis.Funding Information: This study was funded by the National Natural Science Foundation (81801979 and 32160141), the Natural Science Foundation of Hubei Province (No 219CFB358). Declaration of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.