The members of rare actinomycetes were generally
limited in their antimicrobial activity. On the other hand,
varying antibacterial activity was observed for the isolates; 4
strains displayed acute and wide antibacterial spectrum of
more than 4 indicator pathogens (Table 2). Strains A229,
A243, and A281 showed comparatively strong (Φ ≥ 15 mm)
and wide antibacterial spectrum. Furthermore, the active
isolates showed certain selectivity to some pathogens. The
activity against K. pneumoniae was most frequently observed
(83.3%), with relatively high proportion of activities against B.
subtilis and S. aureus being 66.7% and 50.0%, respectively. In
contrast, all test strains showed no inhibition against 4
pathogenic fungi and E. coli, except for the strain A301 which
displayed moderate inhibition against A. fumigatus (data not
showed).