43 Actinobacteria were isolated from the nest of . A phylogenetic analysis of 23 Actinobacteria isolates with different morphotypes showed that they did not form a monophyletic group. Antifungal bioassays exhibited that many strains inhibit both the termite cultivar and the competitor . However, Actinobacteria inhibited the competitor more severely than the termite cultural fungus . Furthermore, two Actinobacteria ( sp. T33 and T37) had a selective antifungal effect on , with the inhibition zone of 25.5 and 8.9 mm, respectively. An actinomycin D was isolated from the strain T33 and had potent antifungal activity against with IC value of less than 3.1 µg/mL. In addition, further bioassays showed that actinomycin D possessed potent antifungal activities against (IC = 0.9 µg/mL), f. sp. (IC = 2.2 µg/mL), (IC = 1.7 µg/mL), (IC = 10.3 µg/mL), (IC = 12.5 µg/mL) and f. sp. (IC = 14.3 µg/mL), which were comparable to those of referenced cycloheximide. The findings of the present study suggest that the termite-associated Actinobacteria have a potential to be used as microbial fungicide.
