title: Effect of modified MRS medium on production and purification of antimicrobial peptide ST4SA produced by Enterococcus mundtii.
abstract: Highest antimicrobial activity of peptide ST4SA (51,200 AU/mL) was recorded after 14 h of growth in MRS broth with optimal production at pH 6.0 or 6.5. Growth of strain ST4SA in the presence of tryptone, yeast extract, or a combination of the two, yielded 102,400 AU/mL. An increase in production of peptide ST4SA to 102,400 AU/mL was recorded in the presence of 20.0 g/L fructose, but decreased to 25,600 AU/mL in the presence of lactose (20.0 g/L) or mannose (20.0 g/L) as sole carbon source. Lower activity (25,600 AU/mL) was recorded when 2.0 g/L K(2)HPO(4) was replaced by 2.0 g/L KH(2)PO(4) in MRS broth. An increase of K(2)HPO(4) to 10.0 g/L and 20.0g/L resulted in higher activity (102,400 AU/mL). Addition of glycerol to MRS broth had a negative effect on peptide ST4SA production. Production of peptide ST4SA required the presence of magnesium sulphate, manganese sulphate and 5.0 g/L sodium acetate. Exclusion of tri-ammonium citrate from the medium resulted in reduction of activity to 3,200 AU/mL. Maximum activity (102,400 AU/mL) was recorded in MRS supplemented with 1.0 ppm Vit. C, DL-6,8-thioctic acid or thiamine, respectively. Growth of Listeria ivanovii susbp. ivanovii ATCC 19119 in the presence of peptide ST4SA (12,800 AU/mL) resulted in 99% cell lysis after 18 h. Improved production of peptide ST4SA was recorded in MRS broth (Biolab) pre-treated with Amberlite XAD-1180. Precipitation with ammonium sulphate, followed by gel filtration chromatography, yielded the highest level of peptide ST4SA. This paper describes the partially deproteination of growth medium to facilitate peptide ST4SA purification.
authors.affiliation: Department of Microbiology, Stellenbosch University, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa.
authors.forename: Svetoslav D
authors.initials: SD
authors.lastname: Todorov
authors.forename: Leon M T
authors.initials: LM
authors.lastname: Dicks
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000302:isolation & purification*; D001433:Bacteriolysis; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D003470:Culture Media / Q000737:chemistry*; D016983:Enterococcus / Q000254:growth & development / Q000378:metabolism*; D008087:Listeria / Q000187:drug effects; D050296:Microbial Viability
chemical_list: D023181:Antimicrobial Cationic Peptides; D003470:Culture Media