Antibacterial Potential of Termite-Associated spp.

Twenty-one strains of termite-associated actinomycetes were tested for their activities against three bacteria. The results showed that nine strains showed bacteriostatic activities against at least one tested bacterium, and the actinomycete YH01, which was isolated from the body surface of the queen of , had potent antibacterial activity. The YH01 was further identified as . Two metabolites roseoflavin () and 8-methylamino-8-demethyl-d-riboflavin () were isolated and purified from YH01. Their structures were determined by NMR, MS, and the related literature. The metabolite showed strong inhibition activities against (MIC = 1.56 μg/mL) and (MIC = 3.125 μg/mL), which were comparable to referenced gentamycin sulfate, with MIC values of 1.56 and 1.56 μg/mL, respectively. Furthermore, the anti-MRSA potential of compound was determined against nine kinds of MRSA strains, with inhibition zones in the ranges of 12.7-19.7 mm under a concentration of 15 μg/6 mm discs and 18.3-22.7 mm under a concentration of 30 μg/6 mm discs. However, metabolite had no inhibitory effect on Gram-negative bacteria. These results suggested that roseoflavin produced by YH01 holds promise for use against Gram-positive bacteria, especially to MRSA.