A PREFERENTIAL ISOLATION PROCEDURE FOR ASPOROGENOUS GRAM-POSITIVE BACTERIA

Abstract

A preferential isolation procedure was devised for asporogenous (Asp), Gram-positive (Gp), aerobic o r facultative anaerobic bacteria which included the genera Arthrobacter, Corynebacterium, Brevibacterium, Microbacterium, Mycobacterium, and Micrococcus (Asp-Gp bacteria). An antibiotics-mixture agar which contained 5 to 10 μg per ml of colistin, 10 to 20 μg per ml of nalidixic acid and 30 μg per ml of cycloheximide was used in the isolation. Using this technique 47 Asp-Gp bacteria representing 26 subgroups of coryneform bacteria and Micrococcus were isolated from 3 soil samples. The method was far more efficient than the standard dilution-plate technique. This preferential method is available to isolate Asp-Gp bacteria from a sample containing about 500-fold more of other Gram-positive and negative bacteria.