Selective Isolation and Enumeration of Actinomycetes using Rifampicin

Addition of rifampicin (5µg/ml) to a number of media allowed the selective isolation of Actinomadura strains from soil and enabled large numbers of ' Thermomonospora (Thm.) chromogena ' and Streptomyces (St.) albus to be isolated from hay and straw. Saccharomonospora (S.) viridis was also tolerant to the antibiotic but was often inhibited by other isolates, while other bacteria including Micropolyspora faeni, 'Thm. fusca', Thermoactinomyces (Tha.) vulgaris and some other Streptomyces spp. were mostly sensitive, even to 2·5 µg/ml. Heating soil samples at 100°C for 15 min further decreased the number of unwanted bacteria growing on glucose-yeast extract agar supplemented with 5 µg/ml of rifampicin.     

Analysis of cellular fatty acids by gas chromatography as a tool in the identification of medically important coryneform bacteria

The fatty acid methyl esters of nineteen unidentified pathogenic coryneform bacteria were analysed by gas-liquid chromatography and the resulting profiles were compared with those of type or reference strains of possibly related species, namely Caseobacter polymorphus, Corynebacterium bovis, C. diphtheriae, C. xerosis and Rhodococcus equi. All of the strains had distinct fatty acid profiles but most of them conformed to a general pattern, with high levels of octadecanoic acids and only trace amounts of 10-methyl octadecanoic acid (tuberculostearic acid). These profiles were very similar to those from C. diphtheriae and C. xerosis but could be differentiated from C. bovis, Cas. polymorphus, R. equi and two unidentified pathogenic strains which had significantly higher levels of tuberculostearic acid.