1,3-PD is an end product of a reductive branch of a glycerol fermentation pathway. 3-HPA (3-hydroxypropionaldehyde) is a direct intermediate of 1,3-PD synthesis and is known to have antimicrobial properties, exerting its toxic effect toward 1,3-PD producers. It has been reported in many papers that 3-HPA accumulation triggers irreversible cessation of cellular growth and metabolic activity of the 1,3-PD producers, especially the enterobacterial strains, although the exact mechanism of its action is not clear. It was shown by mathematical modeling and experimentally confirmed that in Klebsiella pneumoniae.