title: Genetic diversity in proteolytic enzymes and amino acid metabolism among Lactobacillus helveticus strains.
abstract: Lactobacillus helveticus CNRZ 32 is recognized for its ability to decrease bitterness and accelerate flavor development in cheese, and has also been shown to release bioactive peptides in milk. Similar capabilities have been documented in other strains of Lb. helveticus, but the ability of different strains to affect these characteristics can vary widely. Because these attributes are associated with enzymes involved in proteolysis or AA catabolism, we performed comparative genome hybridizations to a CNRZ 32 microarray to explore the distribution of genes encoding such enzymes across a bank of 38 Lb. helveticus strains, including 2 archival samples of CNRZ 32. Genes for peptidases and AA metabolism were highly conserved across the species, whereas those for cell envelope-associated proteinases varied widely. Some of the genetic differences that were detected may help explain the variability that has been noted among Lb. helveticus strains in regard to their functionality in cheese and fermented milk.
authors.affiliation: Department of Nutrition, Dietetics, and Food Sciences and Western Dairy Center, Utah State University, Logan, Utah 84322-8700, USA. jeff.broadbent@usu.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Broadbent
authors.forename: H
authors.initials: H
authors.lastname: Cai
authors.forename: R L
authors.initials: RL
authors.lastname: Larsen
authors.forename: J E
authors.initials: JE
authors.lastname: Hughes
authors.forename: D L
authors.initials: DL
authors.lastname: Welker
authors.forename: V G
authors.initials: VG
authors.lastname: De Carvalho
authors.forename: T A
authors.initials: TA
authors.lastname: Tompkins
authors.forename: Y
authors.initials: Y
authors.lastname: Ardö
authors.forename: F
authors.initials: F
authors.lastname: Vogensen
authors.forename: A
authors.initials: A
authors.lastname: De Lorentiis
authors.forename: M
authors.initials: M
authors.lastname: Gatti
authors.forename: E
authors.initials: E
authors.lastname: Neviani
authors.forename: J L
authors.initials: JL
authors.lastname: Steele
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002611:Cheese / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D052198:Lactobacillus helveticus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D009693:Nucleic Acid Hybridization / Q000235:genetics; D010447:Peptide Hydrolases / Q000235:genetics; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D004269:DNA, Bacterial; D010447:Peptide Hydrolases