Heterologous expression of LamA gene encoded endo-β-1,3-glucanase and CO2 fixation by bioengineered Synechococcus sp. PCC 7002

Abstract

The gene for the catalytic domain of thermostable endo-β-1,3-glucanase (laminarinase) LamA was cloned from Thermotoga maritima MSB8 and heterologously expressed in a bioengineered Synechococcus sp. PCC 7002. The mutant strain was cultured in a photobioreactor to assess biomass yield, recombinant laminarinase activity, and CO2 uptake. The maximum enzyme activity was observed at a pH of 8.0 and a temperature of 70°C. At a CO2 concentration of 5%, we obtained a maximum specific growth rate of 0.083 h–1, a biomass productivity of 0.42 g∙L–1∙d–1, a biomass concentration of 3.697 g∙L–1, and a specific enzyme activity of the mutant strain of 4.325 U∙mg–1 dry mass. All parameters decreased as CO2 concentration increased from 5% to 10% and further to 15% CO2, except enzyme activity, which increased from 5% to 10% CO2. However, the mutant culture still grew at 15% CO2 concentration, as reflected by the biomass productivity (0.26 g∙L–1∙d–1), biomass concentration (2.416 g∙L–1), and specific enzyme activity (3.247 U∙mg–1 dry mass). Open image in new window