Methylglyoxal synthase regulates cell elongation via alterations of cellular methylglyoxal and spermidine content in Bacillus subtilis

•Methylglyoxal (MG) stimulates the expression of the gene encoding methylglyoxal synthase (mgsA) in Bacillus subtilis.•MgsA-overexpressing cells show remarkable elongation compared with mgsA-deficient cells.•SpeB and speE, which encode agmatinase and spermidine synthase, respectively, induce MG biosynthesis.•SpeB- and speE-overexpressing cells have an elongated, rod-shaped morphology.•Expression of mgsA and polyamine genes is regulated by clpP-linked spx. Methylglyoxal regulates cell division and differentiation through its interaction with polyamines. Loss of their biosynthesizing enzyme causes physiological impairment and cell elongation in eukaryotes. However, the reciprocal effects of methylglyoxal and polyamine production and its regulatory metabolic switches on morphological changes in prokaryotes have not been addressed. Here, Bacillus subtilis methylglyoxal synthase (mgsA) and polyamine biosynthesizing genes encoding arginine decarboxylase (SpeA), agmatinase (SpeB), and spermidine synthase (SpeE), were disrupted or overexpressed. Treatment of 0.2mM methylglyoxal and 1mM spermidine led to the elongation and shortening of B. subtilis wild-type cells to 12.38±3.21μm (P