title: Encapsulation of Streptococcus uberis: influence of storage and cultural conditions.
abstract: Streptococcus uberis (n = 100) isolated from bovine mammary secretions were assessed by India ink for expression of capsule. Organisms were evaluated under four conditions; (1) after primary culture on blood agar, (2) following 5 passages on blood agar, (3) after 5 passages in Trypticase Soy Broth (TSB), and (4) after storage in 10% skim milk. Strains from primary culture (44 of 100) were positive for an unstained halo (capsule) by the India ink method. Number of strains expressing capsule decreased greatly after passage and following storage. Freeze-etching followed by electron microscopy confirmed results of India ink preparations. Strains were also cultured in various media to determine influence of medium components on capsule expression. Todd-Hewitt medium supplemented with either serum or egg yolk enhanced the size of capsule expressed. Results of this study may aid researchers investigating the pathogenicity of S. uberis.
authors.affiliation: USDA, ARS, Department of Animal Science, University of Tennessee, Knoxville 37901-1071.
authors.forename: K R
authors.initials: KR
authors.lastname: Matthews
authors.forename: B M
authors.initials: BM
authors.lastname: Jayarao
authors.forename: A J
authors.initials: AJ
authors.lastname: Guidry
authors.forename: E F
authors.initials: EF
authors.lastname: Erbe
authors.forename: W P
authors.initials: WP
authors.lastname: Wergin
authors.forename: S P
authors.initials: SP
authors.lastname: Oliver
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000096:biosynthesis*; D002244:Carbon; D002417:Cattle; D004396:Coloring Agents; D003470:Culture Media; D005260:Female; D005613:Freeze Etching; D008321:Mammary Glands, Animal / Q000382:microbiology; D008414:Mastitis, Bovine / Q000382:microbiology*; D008855:Microscopy, Electron, Scanning; D008892:Milk / Q000382:microbiology; D011309:Preservation, Biological; D013194:Staining and Labeling; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000254:growth & development / Q000472:pathogenicity* / Q000648:ultrastructure; D014774:Virulence
chemical_list: D004396:Coloring Agents; D003470:Culture Media; C028433:chinese ink; D002244:Carbon