title: Scanning electron microscopy of target cells and molecular weight determination of a bacteriocin produced by Lactococcus lactis D53.
abstract: A bacteriocin, lactococcin D53, from Lactococcus lactis strain D53 was partially purified by precipitation with ammonium sulfate and dialysis against deionized water, at which time it precipitated from solution. A native molecular weight was determined by gel filtration, where bacteriocin was detected in two fractions which were measured at 104 and 6.7 kDa. A molecular weight of 7.0 kDa under denaturing conditions was determined by Tricine-SDS-polyacrylamide gel electrophoresis. The molecular weight determinations implied that lactococcin D53 complexed with other macromolecules in its native state in solution. Scanning electron micrographs of Lactobacillus D17 target cells treated with lactococcin D53 showed considerable differences from untreated control cells. The bacteriocin-treated cells had rougher, more granular-looking outer surfaces than untreated cells, which appeared smooth. Counts of viable cells in buffer solution rapidly declined by about one log in target cells treated with bacteriocin.
authors.affiliation: Food Science and Technology Department, University of Nebraska, Lincoln 68583-0919.
authors.forename: L A
authors.initials: LA
authors.lastname: McDougall
authors.forename: W H
authors.initials: WH
authors.lastname: Holzapfel
authors.forename: U
authors.initials: U
authors.lastname: Schillinger
authors.forename: D E
authors.initials: DE
authors.lastname: Feely
authors.forename: J H
authors.initials: JH
authors.lastname: Rupnow
mesh_terms: D000645:Ammonium Sulfate; D001430:Bacteriocins / Q000096:biosynthesis* / Q000737:chemistry* / Q000494:pharmacology; D011232:Chemical Precipitation; D003470:Culture Media; D005516:Food Microbiology; D007778:Lactobacillus / Q000187:drug effects* / Q000648:ultrastructure*; D013294:Lactococcus lactis / Q000254:growth & development / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight
chemical_list: D001430:Bacteriocins; D003470:Culture Media; D000645:Ammonium Sulfate