Pretreatment with 1.5% phenol (30องศา for 30 min) was used in combination with HV agar to isolate streptomycetes from four different soil samples (Table2). When dilution playing was used as the control method, streptomycetes were isolated from all test soil samples as the most abundant group. In contrast, pretreatment with phenol drastically reduced the abundance of streptomycete populations and other bacteria occurring on HV agar. Surviving streptomycetes were detected in small numbers and outnumbered by nonstreptomycetes, including those of the genera Microbispora and Micromonospora. While these streptomycetes grew quickly on the HV isolation plates and formed abundant aerial mycelia with spores after I week of incubation, the growth and sporulation of most nonstreptomycetes were delayed. More than 2 weeks incubation was required to identify the genera of these slow growers.