Putrescine, spermidine and spermine are short-chained aliphatic polyamines that are ubiquitous components in cells and seawater. To study the genes and taxa involved in the transformations of different polyamine compounds and their potential variation among marine environments, we collected surface water samples from nearshore, offshore, and open ocean in the Gulf of Mexico and performed the microcosm incubation of bacterioplankton onboard in the dark at in situ temperature with or without amendments putrescine, spermidine, and sperminein May, 2013.