The sialidase gene from Brevibacterium casei was cloned in pET28a and overexpressed as a histidine-tagged protein in Escherichia coli BL21(DE3). The histidine-tagged sialidase protein was purified and characterized from the crude cell extracts of isopropyl-beta-D-thiogalactopyranoside-induced cells using Ni-NTA agarose chromatography. SDS-PAGE using the purified sialidase indicated a single band at 116 kDa. This sialidase showed maximum activity at a pH of 5.5 and temperature of 37 degrees C. The kinetic parameters K-m and V-max for the artificial substrate 2'-(4-methylumbelliferyl)-alpha-D-N-acetyl-neuraminic acid sodium salt hydrate were 1.69 x 10(-3) mM and 244 mmol.Min(-1)center dot mg(-1), respectively. The sialidase may catalyze the hydrolysis of terminal sialic acids linked by the alpha-(2,3) and alpha-(2,8) linkage of polysialogangliosides, but it does not act on monosialotetrahexosylganglioside (GM1), which offers it a great potential for commercially producing GM1 from polysialogangliosides. (C) 2016 International Union of Biochemistry and Molecular Biology, Inc.