title: Catabolism of serine by Pediococcus acidilactici and Pediococcus pentosaceus.
abstract: The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from L- and D-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and α-aminobutyrate.
authors.affiliation: Agroscope Liebefeld Posieux Research Station ALP, Bern, Switzerland. stefan.irmler@alp.admin.ch
authors.forename: Stefan
authors.initials: S
authors.lastname: Irmler
authors.forename: Tharmatha
authors.initials: T
authors.lastname: Bavan
authors.forename: Andrea
authors.initials: A
authors.lastname: Oberli
authors.forename: Alexandra
authors.initials: A
authors.lastname: Roetschi
authors.forename: René
authors.initials: R
authors.lastname: Badertscher
authors.forename: Barbara
authors.initials: B
authors.lastname: Guggenbühl
authors.forename: Hélène
authors.initials: H
authors.lastname: Berthoud
mesh_terms: D002611:Cheese / Q000382:microbiology; D003001:Cloning, Molecular; D003931:Diacetyl / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D012695:L-Serine Dehydratase / Q000235:genetics / Q000378:metabolism; D010376:Pediococcus / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D012965:Sodium Chloride
chemical_list: D011994:Recombinant Proteins; D012965:Sodium Chloride; D012694:Serine; D019289:Pyruvic Acid; D012695:L-Serine Dehydratase; D003931:Diacetyl