Polyamine metabolism and transport in gut microbes.

Polyamines (putrescine, spermidine, and spermine) are compounds with amino groups at both ends of a hydrocarbon. Polyamines produced by intestinal bacteria suppress chronic inflammation and enhance the intestinal barrier in the colon, and are also transferred into the blood via the colonic epithelium, resulting in significant improvement of host cognitive performance and life extension in mice. Upregulation of polyamine production by gut microbes can help compensate for the aging-associated decrease in polyamine content through the uptake of intestinal luminal polyamine, thereby extending the healthy life expectancy of the host. This review summarizes recent advances in the study of polyamine metabolism and transport in gut microbes, with particular reference to Escherichia coli and the most predominant species of the gut microbiota. Furthermore, we describe polyamine production by a novel hybrid system comprised of multiple gut microbes, as well as from high-polyamine-producing lactic acid bacteria derived from fermented foods.