ACTINOMYCETE DIVERSITY ASSOCIATED WITH FOAMING IN ACTIVATED-SLUDGE PLANTS

Large numbers of mycolic acid-containing actinomycetes were isolated f rom foam and scum samples taken from three activated-sludge sewage-tre atment plants using several selective isolation media, Organisms presu mptively identified as gordonae formed the dominant population in all of the samples, A representative set of these strains have chemical pr operties consistent with their classification in the genus Gordona, Fo rty-eight of the Gordona strains were compared through 165 unit charac ters with the type strains of validly described species of Gordona, Th e resultant data were examined using the Jaccard and simple matching c oefficients and clustering achieved using the unweighted pair group me thod with arithmetic averages algorithm, The numerical classification was only marginally affected by the statistics used or by test error, estimated as 3.92%, The isolates were assigned to five multi-membered and 28 single-membered clusters defined by the simple matching coeffic ient at the 89% similarity level, With few exceptions, the isolates we re sharply separated from the Gordona marker strains, Essentially the same classification was obtained when the test strains were examined u sing a Curie-point pyrolysis mass spectrometric procedure, It can be c oncluded that the gordonae form a heterogeneous taxonomic group, the m embers of which can be distinguished from representatives of validly d escribed species of Gordona.