SPECTROPHOTOMETRIC CHARACTERIZATION OF PIGMENTS PRODUCED BY STAPHYLOCOCCUS EPIDERMIDIS STRAINS ISOLATED FROM BOVINE UDDERS.

Sandvik, Olav (National Animal Disease Laboratory, Ames, Iowa), and Richard W. Brown. Spectrophotometric characterization of pigments produced by Staphylococcus epidermidis strains isolated from bovine udders. J. Bacteriol. 89:1201-1208. 1965.-Spectrophotometric analysis of methanol-extracted pigments of 70 isolates, representing 48 strains of Staphylococcus epidermidis, exhibited absorption curves that were classified into seven types, designated I, II, III, IV, V, VI, and a S. aureus type. Two subtypes were included in types I and III. All nonpigmented cell extracts were classified as type I. One of the six numbered type absorption curves was obtained with the majority of isolates. Three isolates gave an absorption curve that was similar to the curve produced by extracts of five of seven S. aureus strains, thus the designation S. aureus type. The differences in pigment complexes indicated by the various absorption curves of methanol extracts were substantiated by column-chromatography studies. Generally, pigments of types II to VI, as produced by representative strains, were of a xanthophyllic nature, whereas, the S. aureus type pigment studied was carotenelike. Analyses of representative strains showed that the type of spectral absorption curves did not change whether the organisms were carried in vitro and tested through 3 months, or isolated repeatedly from infected udders for periods up to 8 months. The method of determining the spectral absorption curves of whole-cell methanol extracts provides an additional tool for differentiating strains of S. epidermidis that can be used in enzootiological studies of udder infections.