Bacterial strain NYT501, which we previously isolated from soil, was identified as Stenotrophomonas maltophilia, and it was confirmed that this strain produces an intracellular beta-N-acetylhexosaminidase exhibiting transglycosylation activity. Several properties of this enzyme were characterized using a partially purified enzyme preparation. Using N,N'-diacetylchitobiose (GlcNAc)(2) and N,N',NaEuro(3)-triacetylchitotriose (GlcNAc)(3) as substrates and dried cells of this bacterium as a whole-cell catalyst, chitin oligosaccharides of higher degrees of polymerization were synthesized. (GlcNAc)(3) was generated from (GlcNAc)(2) as the major transglycosylation product, and a certain amount of purified sample of the trisaccharide was obtained. By contrast, in the case of the reaction using (GlcNAc)(3) as a substrate, the yield of higher-degree polymerization oligosaccharides was comparatively low.