Kinetic and thermodynamic properties of alginate lyase and cellulase co-produced by Exiguobacterium species Alg-S5.

In an effort to screen out the alginolytic and cellulolytic bacteria from the putrefying invasive seaweed Sargassum species accumulated off Barbados' coast, a potent bacterial strain was isolated. This bacterium, which simultaneously produced alginate lyase and cellulase, was identified as Exiguobacterium sp. Alg-S5 via the phylogenetic approach targeting the 16S rRNA gene. The co-produced alginate lyase and cellulase exhibited maximal enzymatic activity at pH 7.5 and at 40°C and 45°C, respectively. The Km and Vmax values recorded as 0.91mg/mL and 21.8U/mg-protein, respectively, for alginate lyase, and 10.9mg/mL and 74.6U/mg-protein, respectively, for cellulase. First order kinetic analysis of the thermal denaturation of the co-produced alginate lyase and cellulase in the temperature range from 40°C to 55°C revealed that both the enzymes were thermodynamically efficient by displaying higher activation energy and enthalpy of denaturation. These enzymatic properties indicate the potential industrial importance of this bacterium in algal biomass conversion. This appears to be the first report on assessing the efficacy of a bacterium for the co-production of alginate lyase and cellulase.