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A novel β-N-acetylglucosaminidase (GlcNAcase) inhibitor named TMG-chitotriomycin (1) was isolated from the culture filtrate of Streptomyces anulatus NBRC13369. The strain produced 1 only when colloidal chitin was used as the sole carbon source in the production medium. The structure of 1 was determined by spectral and constitutive sugar analyses of the corresponding alditol derivatives to be an equilibrated mixture of R-D-N,N,N-triMeGlcNH2-(1,4)-β-D-GlcNAc-(1,4)-β-D-GlcNAc-(1,4)-D-GlcNAc and its C-2 epimer of the reducing end residue. TMG-chitotriomycin (1) showed potent and selective inhibition of insect and fungal GlcNAcases with no inhibition of mammalian and plant GlcNAcases. In contrast, the known GlcNAcase inhibitor nagstatin potently inhibited all GlcNAcases. It should be emphasized that synthesized D-N,N,N-triMeGlcNH2, which is the component sugar of 1, showed no inhibition of the insect Spodoptera litura GlcNAcase. These results suggest that the (GlcNAc)3 unit positioned at the reducing end of 1 is essential for its enzyme inhibitory activity. The unique inhibitory spectrum of 1 will be useful to study chitinolytic systems and to develop selective fungicides or pesticides.

This study examined the microbiological features of the three reference strains of Bacillus thuringiensis whose noninsecticidal parasporal inclusions contain anticancer parasporins (PS2, PS3, and PS4). Morphometric analysis showed that the sizes and aspect ratios of the spores of these strains were in the range of those reported for the Bacillus cereus/B. thuringiensis group. The API 50CH test revealed that the carbohydrate utilization profiles of these strains were typical of the B. cereus/B. thuringiensis group. These parasporin producers proved resistant to ampicillin, and induced b-hemolysis on sheep blood agar. Overall results show that there is no significant difference in several phenotypic key characters between B. thuringiensis strains with PS2, PS3, and PS4 and those with insecticidal crystal proteins.

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