title: Putrescine production via the agmatine deiminase pathway increases the growth of Lactococcus lactis and causes the alkalinization of the culture medium.
abstract: Lactococcus lactis is the most important starter culture organism used in the dairy industry. Although L. lactis species have been awarded Qualified Presumption of Safety status by the European Food Safety Authority, and Generally Regarded as Safe status by the US Food and Drug Administration, some strains can produce the biogenic amine putrescine. One such strain is L. lactis subsp. cremoris CECT 8666 (formerly L. lactis subsp. cremoris GE2-14), which was isolated from Genestoso cheese. This strain catabolizes agmatine to putrescine via the agmatine deiminase (AGDI) pathway, which involves the production of ATP and two ammonium ions. The present work shows that the availability of agmatine and its metabolization to putrescine allows for greater bacterial growth (in a biphasic pattern) and causes the alkalinization of the culture medium in a dose-dependent manner. The construction of a mutant lacking the AGDI cluster (L. lactis CECT 8666 Δagdi) confirmed the latter's direct role in putrescine production, growth, and medium alkalinization. Alkalinization did not affect the putrescine production pattern and was not essential for increased bacterial growth.
authors.affiliation: Instituto de Productos Lácteos de Asturias, IPLA-CSIC, Paseo Rio Linares s/n, 33300, Villaviciosa, Spain, beadelrio@ipla.csic.es.
authors.forename: Beatriz
authors.initials: B
authors.lastname: del Rio
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Linares
authors.forename: Victor
authors.initials: V
authors.lastname: Ladero
authors.forename: Begoña
authors.initials: B
authors.lastname: Redruello
authors.forename: Maria
authors.initials: M
authors.lastname: Fernández
authors.forename: Maria Cruz
authors.initials: MC
authors.lastname: Martin
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Alvarez
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002611:Cheese / Q000032:analysis; D003470:Culture Media / Q000737:chemistry*; D004269:DNA, Bacterial / Q000235:genetics; D005285:Fermentation; D059022:Food Safety; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development*; D005810:Multigene Family; D009154:Mutation; D011700:Putrescine / Q000096:biosynthesis*
chemical_list: D064751:Ammonium Compounds; D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D006867:Hydrolases; C019626:agmatine deiminase; D011700:Putrescine