Purification and characterization of chitinases from Clostridium sp. E-16 isolated from the intestinal tract of the South American sea lion (Otaria flavescens)

Abstract

This study was undertaken to examine the properties of chitinases purified from Clostridium sp. E-16, an intestinal bacterium of the South American sea lion (Otaria flavescens). We also elucidated the taxonomic status of this bacterium to better understand the role of intestinal anaerobic bacteria in marine animals. Two chitinases were purified with ammonium sulfate precipitation, affinity chromatography and preparative electrophoresis from culture supernatant fluid from Clostridium sp. E-16. Molecular mass was estimated to be 77 kDa for chitinase 1 and 98 kDa for chitinase 2 by SDS-PAGE. Optimum pH of both purified chitinases was between 5.0 and 7.0. Chitinase 1 was inhibited with Cu(2+), Fe(2+), Hg(2+) and Zn(2+), while chitinase 2 was inhibited with Fe(2+). Phylogenetic analysis using 16S ribosomal DNA (rDNA) sequences and phenotypic characterization revealed that Clostridium sp. E-16 was closely related to Clostridium baratii. It is likely that chitinases from C. baratii or a C. baratii-like bacterium play an important role in degradation of chitin in the intestinal tract of the South American sea lion and in marine environments. This is the first report of chitinase purification and characterization from a marine Clostridium strain.