Amidases can be assigned into two families according to their amino acid sequences. Three amidases (Dt-Amis) were mined and identified from genome of Delftia tsuruhatensis. Homology analysis demonstrated that Dt-Ami 2 and Dt-Ami 6 belonged to amidase signature (AS) family, while Dt-Ami 7 belonged to nitrilase superfamily. AS amidases were shown to hydrolyze a wide spectrum of amides. Kinetic analysis demonstrated that the extension of chain length of aliphatic amides considerably decreased the K-m values, and the turnover numbers (k(cat)) were high with linear aliphatic amides as substrates. Dt-Ami 2 showed maximum activity near a quite alkaline pH (11.0) and exhibited opposite enantioselectivity to Dt-Ami 6. Furthermore, a novel bioprocess for hydrolysis of 1-cyanocyclohexaneacetamide was developed using Dt-Ami 6 as biocatalyst, resulting in >99% conversion within 1.5 hat a substrate loading of 100 g/L by 0.5 g/L of Escherichia coli cells. On the other hand, nitrilase superfamily amidase only hydrolyzed aliphatic amides. The K-m values of Dt-Ami 7 were considerably increased with the extension of chain length of aliphatic amides. The characterized enzymes from different families showed distinct biochemical characteristics and catalytic properties, leading to a better understanding of the two super amidase family members. (C) 2016 Elsevier Inc. All rights reserved.