Spectrophotometric Characterization of Pigments Produced by Staphylococcus epidermidis Strains Isolated from Bovine Udders

Abstract

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.

Color of Cultures of Staphylococcus epidermidis Determined by Spectral Reflectance Colorimetry

“…The cultures of S. epidermidis used in this study were isolated from milk samples obtained from an experimental herd of 20 cows sampled at weekly intervals. The methods of isolation, identification, and storage have been described (3). The organisms were also tested for pigment production by the method of analyzing spectrophotometrically the methanol-extracted pigments (3).…”

“…In a previous study, strains of Staphylococcus epidermidis isolated from bovine udders were differentiated on the basis of the absorption spectra of the pigments extracted with methanol (3). The method demonstrated qualitative differences in the pigments and, to some extent, quantitative differences in pigment production, but it did not provide information on the color of the colonies.…”