Bovine mastitis is caused mainly by certain Staphylococcus and Streptococcus species. The sequences of the 16S-23S rRNA spacer regions were determined for the nine species which cause mastitis: Staphylococcus aureus, Staphylococcus chromogenes, Staphylococcus epidermidis. Staphylococcus hyicus, Staphylococcus simulans, Staphylococcus xylosus. Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis. Significant variation was found between the spacer sequences of different species with the lengths of the spacers varying from 240 to 461 bp. Between genera the spacers shared only short conserved regions (8-9 bp) and within genera the sequence identities varied from 53 to 85%. This variation made it possible to construct specific primer pairs for these species and genera. The specificities of these primers were tested with 25 bacterial species and 51 isolates from cattle with clinical mastitis. The DNA-based identification of the mastitis species was mostly successful.
The hypothesis that biodegradable surfactants stimulate the attachment of biodegradation-competent bacteria to surfaces has been re-evaluated using a variant of the surfactant-degrading bacterium Pseudomonas sp. DES1 designated Pseudomonas sp. DES2. This variant was identical to the parental strain in terms of its carbon-utilization patterns and alcohol dehydrogenase and alkylsulfatase complements (enzymes involved in surfactant biodegradation), but differed markedly in its growth characteristics when using sodium dodecyl triethoxysulfate or triethylene glycol dodecyl ether as secondary carbon sources. Pseudomonas sp. DES1 exhibited diauxie in these surfactant-based culture media in contrast to Pseudomonas sp. DES2, which exhibited single-phase growth. Pseudomonas sp. DES2 did not attach to river sediment in a microcosm system when challenged with a dose of either surfactant, although it did biodegrade the substrate. In contrast, Pseudomonas sp. DES1 attached to the river sediment whilst biodegrading the test substrate. It is concluded that the ether-scission system, which is responsible for primary biodegradation of both substrates, is deregulated in Pseudomonas sp. DES2 in contrast to that in Pseudomonas sp. DES1, and that, contrary to a previous hypothesis, biodegradable surfactants do not necessarily stimulate the attachment of biodegradation-competent bacteria during their biodegradation.