title: Bacteriocin production by Streptococcus thermophilus in complex growth media.
abstract: OBJECTIVE
  To test if the production of bacteriocins by Streptococcus thermophilus is influenced when grown in various complex media commonly used for the culturing of lactic acid bacteria.
  
  
  RESULTS
  Forty-one strains of S. thermophilus were screened for the production of bacteriocins in tryptone/yeast extract/lactose (TYL), M17-lactose (M17L), M17-glucose (M17G) and MRS media. Two strains, ST144 and ST145, were identified as novel bacteriocin producers, with constitutive production observed only in M17G. Strains ST110, ST114 and ST134 constitutively produced bacteriocins in all growth media but ST114 required growth in MRS for its antimicrobial activity to persist in a 24 h culture. The addition of a synthetic quorum sensing peptide (BlpC) induced bacteriocin production by ST106 in all media tested; and by ST118 in TYL and M17L. Strain ST109, which constitutively produced a bacteriocin in TYL and M17 broths, required BlpC induction when grown in MRS. Real-time PCR analysis showed that the natural expression of blpC in ST109 was lower when grown in MRS, suggesting that something in medium interfered with the blp quorum sensing system.
  
  
  CONCLUSIONS
  As the choice of growth medium influences both bacteriocin production and peptide stability, several types of production media should be tested when screening for novel bacteriocin-producing strains of S. thermophilus.
authors: Dairy and Functional Food Research Unit, Agricultural Research Service, USDA, 600 E. Mermaid Lane, Wyndmoor, PA, 19038, USA. john.renye@ars.usda.gov.
authors: J A
authors: JA
authors: Renye
authors: Dairy and Functional Food Research Unit, Agricultural Research Service, USDA, 600 E. Mermaid Lane, Wyndmoor, PA, 19038, USA.
authors: G A
authors: GA
authors: Somkuti
authors: Agricultural Research Center of Mabegondo (CIAM), Xunta de Galicia, 15318, Abegondo, Spain.
authors: J I
authors: JI
authors: Garabal
authors: Dairy and Functional Food Research Unit, Agricultural Research Service, USDA, 600 E. Mermaid Lane, Wyndmoor, PA, 19038, USA.
authors: D H
authors: DH
authors: Steinberg
mesh_terms: D001430:Bacteriocins / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D053038:Quorum Sensing / Q000187:drug effects; D048249:Streptococcus thermophilus / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001430:Bacteriocins; D003470:Culture Media
keywords: Antimicrobial activity; Bacteriocin; Growth medium; Quorum sensing; Streptococcus thermophilus