Distribution of the Actinomycetes in the Republic of South Africa Investigated Using a Newly Developed Isolation Method

Abstract

A total of 93 soil samples were collected at 3 sites in the southern, at 4 sites in the northwestern, and at 2 sites in the northeastern regions of the Republic of South Africa. When these samples were subjected to the conventional dilution plate method for the isolation of actinomycetes, the genus Streptomyces was found to be dominant, and of 135 total isolates, 53 (39%) were rare actinomycetes. However, the newly developed high-speed centrifugation method enabled us to isolate 335 isolates, of which 295 (88%) were rare actinomycete strains. These included the rare genera Planomonospora and Planobispora, which have been known to have a very low population density in soils. These two genera were detected only in soil samples collected from the extremely arid area, called “Namaqualand”, in the northwestern region of the Republic of South Africa.